«*EPA
United States
Environmental Protection
Agency
Municipal Environmental Research EPA-600 9-79-011
Laboratory May 1979
Cincinnati OH 45268
Research and Development
Performance and
Upgrading of
Wastewater
Stabilization Ponds
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into 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. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This document js available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/9-79-011
May 1979
PERFORMANCE AND UPGRADING OF WASTEWATER STABILIZATION PONDS
Proceedings of a Conference
Held August 23-25, 1978, at Utah State University
Logan, Utah
Edited by
E. Joe Middlebrooks
Donna H. Falkenborg
Ronald F. Lewis
Grant Number R805842
Project Officer
Ronald F. Lewis
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
ii
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. The complexity of the environment and
the interplay between its components require a concentrated and integrated
attack on the problem.
Research and development is that necessary first step in problem solution
and it involves defining the problem, measuring its impact, and searching
for solutions. The Municipal Environmental Research Laboratory develops new
and improved technology and systems for the prevention, treatment, and manage-
ment of wastewater and solid and hazardous waste pollutant discharges from
municipal and community sources, for the preservation and treatment of public
drinking water supplies, and to minimize the adverse economic, social, health,
and aesthetic effects of pollution. This publication is one of the products
of that research; a most vital communications link between the researcher
and the user community.
As part of these activities, these proceedings were prepared to make
available to the sanitary engineering community the results of many studies
conducted by EPA and other agencies on the upgrading of wastewater lagoon
effluents for the removal of algae, bacteria, and chemical components from
lagoon effluent.
Francis T. Mayo
Director
Municipal Environmental Research
Laboratory
iii
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ABSTRACT
A conference, jointly funded by Utah State University and the Office of
Research and Development, U.S. Environmental Protection Agency, on the per-
formance and upgrading of wastewater stabilization ponds was held August 23-
25, 1978, at the College of Engineering, Utah State University, Logan, Utah.
The Proceedings contain 18 papers discussing and describing the design,
operation, performance and upgrading of lagoon systems. Performance data for
facultative and aerated lagoons collected at numerous sites throughout the
USA are presented. Design criteria and the applicability of performance data
to design equations are discussed. Rock filters, intermittent sand filters,
microscreening and other physical-chemical techniques, phase isolation, land
application, and controlled environment aquaculture were evaluated as methods
applicable to upgrading lagoon effluents. The proceedings conclude with a
presentation on the costs associated with the construction, operation and
maintenance of lagoon systems.
This report was submitted in partial fulfillment of Grant No. R805842
by the Utah Water Research Laboratory, Utah State University, under the
sponsorship of the U.S. Environmental Protection Agency.
iv
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CONTENTS
Page
INTRODUCTORY REMARKS
Francis T. Mayo 1
INTRODUCTION AND OBJECTIVES OF SYMPOSIUM
Robert L. Bunch 2
HISTORICAL REVIEW OF OXIDATION PONDS AS THEY IMPACT
SECONDARY TREATMENT AND WATER QUALITY
Ronald F. Lewis 4
RECENT AMENDMENTS TO SECONDARY TREATMENT REGULATIONS
FOR SUSPENDED SOLIDS IN LAGOONS
Stanley M. Smith ............ 15
EVALUATION OF FACULTATIVE WASTE STABILIZATION POND
DESIGN
Brad A. Finney and E. Joe Middlebrooks 18
WASTE STABILIZATION POND SYSTEMS
Earnest F. Gloyna and Lial F. Tischler 37
DESIGN AND CONSTRUCTION OF WASTEWATER STABILIZATION PONDS
Earl C. Reynolds, Jr., and Scott B. Ahlstrom 51
A CASE HISTORY EXAMINATION OF LAGOON UPGRADING
TECHNIQUES
L. Sheldon Barker 63
FIELD EVALUATION OF ROCK FILTERS FOR REMOVAL OF
ALGAE FROM LAGOON EFFLUENTS
Kenneth J. Williamson and Gregory R. Swanson 75
COMMENTS ON FIELD EVALUATION OF ROCK FILTERS FOR REMOVAL
OF ALGAE FROM LAGOON EFFLUENTS
M. L. Cleave ............ 88
AUTHOR'S RESPONSE TO COMMENTS BY M. L. CLEAVE
Kenneth J* Williamson and Gregory R. Swanson 90
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CONTENTS (Continued)
Page
MICROSCREENING AND OTHER PHYSICAL-CHEMICAL TECHNIQUES
FOR ALGAE REMOVAL
Richard A. Kormanik and Joe Bob Cravens 92
POND ISOLATION AND PHASE ISOLATION FOR CONTROL OF
SUSPENDED SOLIDS AND CONCENTRATION IN SEWAGE
OXIDATION POND EFFLUENTS
Ben L. Koopman, John R. Benemann, and W. J. Oswald . . . 104
AN INTEGRATED, CONTROLLED ENVIRONMENT AQUACULTURE
LAGOON PROCESS FOR SECONDARY OR ADVANCED
WASTEWATER TREATMENT
S. A. Serf ling and C. Alsten 124
INTERMITTENT SAND FILTRATION TO UPGRADE LAGOON
EFFLUENTS
James H. Reynolds, Jerry S. Russell, and E. Joe Middlebrooks . 146
LAND APPLICATION OF LAGOON EFFLUENTS
A. T. Wallace 166
DISINFECTION OF LAGOON EFFLUENTS
Bruce A. Johnson 173
COST ESTIMATES FOR OXIDATION POND SYSTEMS
Michael F. Torpy ............ 184
PERFORMANCE OF AERATED WASTEWATER STABILIZATION
PONDS
E. J. Middlebrooks, J. H. Reynolds, and C. H. Middlebrooks . 200
AUTHOR INDEX 208
SUBJECT INDEX 211
vi
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INTRODUCTORY REMARKS
Francis T. Mayo*
It is always a pleasure to share
with peers the important fruits of
research and developmental activities.
This symposium on the performance
and upgrading of wastewater stabilization
ponds offers such an occasion. It is an
important follow-up to the 1974 meeting
(also held in Logan, Utah), devoted to
summarizing preliminary results of pilot
methods for removal of algae from lagoon
effluents and other information on design
and operation of wastewater lagoons. The
results of EPA's recently concluded
5-year program on lagoon performance and
upgrading will be summarized at this
symposium along with important work by
other organizations. The work includes
data on performance of full-scale facul-
tative and aerated lagoons; disinfection
of lagoon effluents; and the use of
slow-rock filters, intermittent slow-sand
filters, phase-isolation ponds, and land
application as means of upgrading lagoon
effluents.
Lagoon systems have historically
enjoyed some important advantages over
•Francis T. Mayo is Director,
Municipal Environmental Research Labora-
tory, U.S. Environmental Protection
Agency, Cincinnati, Ohio.
more conventional wastewater treatment
systems because of minimal power con-
sumption, generally lower capital costs
and lower operation and maintenance
costs. However, the apparent simplicity
of lagoon systems should not imply that
haphazard designs or inadequate data can
be tolerated, and still provide required
levels of wastewater treatment. Because
of the greater number of unknowns, lagoon
systems can be more complex to design
than conventional treatment systems.
The studies that are going to be
reviewed indicate that well designed
and operated wastewater lagoon systems
can be tailored to meet various levels of
effluent requirements and still retain
the features attractive to small com-
munities—low capital costs and low
operating and maintenance costs.
It is important that we make avail-
able to consulting engineers, local
governments, and regulatory agencies,
sufficient knowledge of the design
and performance of lagoon systems.
They can then adequately consider the
array of alternative systems available
for solving individual wastewater treat-
ment problems, especially for the smaller
communities.
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INTRODUCTION AND OBJECTIVES OF SYMPOSIUM
Robert L. Bunch*
On behalf of the Municipal Environ-
mental Research Laboratory of the
U.S. Environmental Protection Agency
(EPA), I wish to welcome you to this
"Symposium on Performance and Upgrading
Wastewater Stabilization Ponds." You are
a select triad consisting of regulatory
officials, researchers and implementors
of stabilization ponds. In the next two
and one-half days we intend to pass on to
you the most recent results of our
on-going research programs on stabiliza-
tion ponds. Ample time also has been
allotted for panel discussions. Hope-
fully, each participant has brought a
problem he can present during the dis-
cussions. To find the best solutions to
these problems will require your active
participation in the group discussions.
This is the second time the Office
of Research and Development of the U.S.
Environmental Protection Agency and Utah
State University have cooperated in
presenting a symposium on wastewater
stabilization ponds. The first meeting
was during August 197**- The tone of the
first meeting was quite different than
the one here today. In 1974 there was an
overall negative attitude as to the
suitability of lagoons in meeting the
secondary treatment requirements without
supplemental treatment. There were
several events that lead to that feeling.
The Federal Water Pollution Control
Act Amendments of 1972 has established
the minimum performance requirements
for publicly-owned treatment works. One
of the requirements of this Act was that
by July 1977 publicly-owned treatment
works must meet effluent limitations
based on secondary treatment as defined
by the EPA administrator. On August 17,
1973, EPA published Secondary Treatment
*Robert L. Bunch is Chief, Treat-
ment Process Development Branch, Waste-
water Research Division, Municipal
Environmental Research Laboratory,
Environmental Protection Agency, Cincin-
nati, Ohio.
Standards in the Federal Register, Vol.
38, No. 159, Part II, p. 22298-22299.
These regulations stated: (a) the
five-day biochemical oxygen demand
(BOD^) and suspended solids (SS) shall
not exceed an arithmetic mean value of 30
mg/1 for effluent samples collected in a
period of 30 consecutive days nor 45 mg/1
for samples collected in seven consecu-
tive days; (b) the arithmetic mean of
the effluent 6005 and SS values deter-
mined on samples collected in a period
of 30 consecutive days shall not exceed
15 percent of the arithmetic mean of
8005 and SS values determined on in-
fluent sampes collected at approximately
the same times during the same period;
and (c) the geometric mean of the
fecal coliform bacteria in the effluent
shall not exceed 200 per 100 milli-
liters for samples collected in a period
of 30 consecutive days, nor 400 per
100 milliliters for samples collected in
a period of seven consecutive days.
A report "Lagoon Performance and the
State of Lagoon Technology" prepared by
George Barsom of Ryckman, Edgerly,
Tomlinson and Associates, Inc. , gave no
assurance that there were existing lagoon
designs capable of meeting the secondary
treatment standards. As a result of
these events, EPA decided to put research
funds into developing inexpensive methods
for upgp-ading lagoons. The first projects
funded were to have a quick return so
that the technology could impact the
construction grants program and meet the
July 1, 1977, deadline for achieving
secondary treatment. Some of the up-
grading techniques investigated were the
intermittent sand filter, submerged rock
filter and land application of algae
laden effluents. The results of these
projects were presented at the first
symposium in 1974.
As a result of an extensive review
of the literature on waste stabiliza-
tion ponds and the information presented
at the last lagoon symposium, EPA arrived
at the following conclusions concerning
lagoons. Of the 4,000 publicly-owned
waste treatment lagoons for the United
States, over 90 percent of them are
located in small rural communities and
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are designed for a flow of less than 1
mgd. 'There is a wide variation in the
design of the lagoon system and long-term
performance data are generally lacking.
Most of the results were from infrequent
grab sampling, particularly for contin-
uous discharge facultative lagoons and
aerated lagoons. The data that were
available indicated that multiple cell
lagoons were better than one large
lagoon and that the effluent quality is
deteriorated either by large amounts
of algae in lagoon effluents during the
summer period or by icing over of the
lagoons in winter, resulting in anaerobic
conditions or simply by rising levels of
soluble organics in the effluent due to
the drastic decrease in biological
activity during cold winters.
In the past 5 years, EPA has at-
tempted to determine how effectively
well-designed and well-managed waste
treatment lagoons operate throughout
all seasons of the year. Because of the
preponderance of continuous-discharge
facultative and aerated lagoons in
municipal use, the evaluation was con-
fined to these two types. Four faculta-
tive and five aerated wastewater treat-
ment lagoon systems were included in our
survey. The sites were carefully chosen
so that ranges of climatic and regional
conditions would be covered. In that the
majority of the existing lagoons serve
small communities, candidate lagoons
serving around 5,000 people or less were
chosen. The sampling and analytical data
gathering period was for at least 1
year.
Since the last symposium, EPA has
also sponsored grants on nutrient
control, disinfection, and algae removal.
The total outlay of research funds by EPA
since 1973 on lagoon studies has been
over $1.5 million.
Today there is a different attitude
toward lagoons than at our meeting
in 1974. Today, there is more confidence
both in the capabilities of conventional
pond systems and in the use of supplemen-
tary devices to upgrade the existing
lagoons. The Environmental Protection
Agency believes that wastewater treatment
ponds play a vital role in the Nation's
water pollution control strategy.
Because of their advantages of simplic-
ity, low cost and minimal energy require-
ments, ponds should always be considered
as viable options of wastewater treatment
for smaller communities. Two pieces
of legislation passed by EPA that have
aided the use of lagoons are deletion
of the fecal coliform bacteria limitation
from the definition of secondary treat-
ment on July 26, 1976, and the granting
of a variance on October 7, 1977, which
allows the EPA Regional Administrator to
adjust the suspended solids limitation
for individual small ponds. This vari-
ance from the definition of secondary
treatment applies only to ponds with a
design capacity of 2 mgd or less. This
standard applies to publicly owned
treatment works and is not directly
applicable to private or federal waste-
water treatment ponds.
The Municipal Environmental Research
Laboratory has initiated the preparation
of" a lagoon design manual. The manual
will include design criteria, case
histories, and cost estimates for all
feasible types of stabilization ponds.
It is estimated that it will take 2 years
to prepare and publish this manual. This
symposium is designed to get the latest
information on lagoons into your hands
today so that it will impact newly
designed lagoons and give you guidance on
upgrading of existing lagoons.
EPA desires to be responsive to your
needs and will be guided by your recom-
mendations for future studies on lagoons.
If you have suggestions, please make them
known to me here at the meeting or when
you return home.
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HISTORICAL REVIEW OF OXIDATION PONDS AS THEY IMPACT
SECONDARY TREATMENT AND WATER QUALITY
Ronald F. Lewis*
BACKGROUND
The Federal Water Pollution Control
Act Amendments of 1972 (the Act) estab-
lished an extensive program to restore
and maintain the biological, physical,
and chemical quality of the Nation's
waters. As part of this program, ef-
fluent limitations were to be established
for point discharge waste sources. For
municipal wastewater treatment the Act
required EPA to define the effluent
quality that can be achieved by secondary
treatment. More stringent effluent
requirements may be necessary to meet
water quality standards.
For both municipal and industrial
wastewater treatment, oxidation ponds
can play a significant role in helping to
meet the established effluent limita-
tions. Oxidation ponds are relatively
easy to design, construct, and maintain,
hence their popularity for wastewater
treatment. The basic simplicity of
oxidation ponds results in a lack of
control over the microbial and chemical
reactions in the ponds. It is common to
find that ponds are not able to achieve
the required level of treatment when used
as the only treatment process.
In spite of the fact that oxidation
ponds have been used for wastewater
treatment for decades, continuing re-
search needs to be undertaken to improve
oxidation pond performance to meet
progressively stringent effluent limita-
tions. In the mid-twenties, cities in
California, Texas, and North Dakota
were using lagoons as a means of treating
municipal sewage. However, it was
not until several years later that design
guidelines were developed. Consequently,
*Ronald F. Lewis is Microbiologist,
Biological Treatment Section, Treat-
ment Process Development Branch, Waste-
water Research Division, Municipal
Environmental Research Laboratory,
Environmental Protection Agency, Cin-
cinnati, Ohio.
it was more by accident, the availability
of a "pot-hole" perhaps, than by design
that lagoons (oxidation ponds) evolved as
a viable method for treating raw sewage.
DEFINITIONS
There are many types of aerobic
wastewater treatment ponds which are
used to achieve the objective of satis-
factory wastewater treatment such as:
r. £ h ° i ° J! .X H i ll .§ i ! — — £ 5 — — —
Th~es"e"~"pon"ars~^¥Fe~~d~e signed
to rely on- photosynthetic
oxygenation for a portion
of the oxygen needed for
waste treatment. They pri-
marily are facultative.
Terminology used to describe
these ponds includes: oxida-
tion ponds, waste stabilization
ponds or lagoons, aerobic
lagoons, facultative lagoons.
r£±^^]l^A£Il_££I1^5_- This
type relies on evaporation
and percolation to exceed
inflow so that there may
be no discharge during part or
all of a year. Photosynthetic
biological activity will exist
in such ponds.
-aerated ponds - Such ponds do
not rely solely on photosyn-
thetic oxygenation; aeration is
supplied by mechanical means.
These ponds also contain algae
(suspended solids generally 150
mg/1 or less) unless, as in the
case of the oxidation ditch,
the detention period is so
short and the aeration and
mixing are sufficient to allow
a high concentration of mixed
liquor volatile suspended
solids (generally 800 mg/1 or
more) inhibiting sunlight
penetration and algal growth.
An oxidation pond is a large,
relatively shallow basin designed for
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long term detention of a wastewater which
may or may not have received prior
treatment. While in the pond, biological
activity oxidizes the influent wastes and
results in the synthesis of micro-
organisms and algae. The effluent will
contain low concentrations of soluble BOD
and varying amounts of suspended solids
in the form of microbial floe and algae.
Oxidation ponds are widely used in
the United States. From 45 lagoons
in 19^5 located in a few states, today
the use has spread to all of the 50
states and over 4000 lagoons. Approxi-
mately 93 percent of the lagoons are
0.5 mgd or less according to recent
statistics kept in the Storet File.
This technique of treating municipal
sewage has provided low cost treatment
for many communities.
Ponds have been used because opera-
tion is simple, operating costs are
low, and land is available. There is a
wide variation in the design of the
ponds. Pond loadings increase and
retention times decrease from north
to south in the United States, reflecting
the effect of differing climatic condi-
tions and their effect on performance.
Until the last four or five years,
comprehensive performance data from
oxidation ponds usually have not been
available. Effluent sampling commonly
is lacking or is infrequent grab sam-
pling. Thus, there was a dearth of
data that could relate effluent quality
to design or actual loading, to varia-
tions in influent load, to climatic
conditions, or to effluent limitations.
SECONDARY TREATMENT REQUIREMENTS
Publication of the definition of
secondary treatment (1) in the early
1970s focused attention on the fact that
oxidation ponds had difficulty in
meeting the requirements. The effluent
limitations for municipal wastewater
treatment were:
-The arithmetic mean of values
of BOD5 and suspended solids
for effluent samples collected
in a period of 30 consecutive
days shall not exceed 30 mg/1
respectively, and for effluent
samples collected in a period
of seven consecutive days shall
not exceed 45 mg/1 respective-
ly-
-The arithmetic mean of the
8005 and suspended solids for
effluent samples collected in a
period of 30 consecutive days
shall not exceed 15 percent of
the arithmetic mean of the
values of the influent samples
collected at approximately the
same times during the same
period (85 percent removal).
-The geometric mean of the
value for fecal coliform
bacteria for effluent samples
collected in a period of 30
consecutive days shall not
exceed 200 per 100 milliliters
and for effluent samples
collected in a period of seven
consecutive days shall not
exceed 400 per 100 milliliters.
-The effluent values of pH
shall remain within the limits
of 6 .0 and 9.0.
An interpretation of 304 (d) of the 1972
FWPCF amendments was that the defi-
nition of secondary treatment should be
based on technical considerations
rather than water quality or economic
considerations. In the record of
legislative history of the 1972 Act,
Congress seemed to indicate that the
term "seconday treatment" be utilized in
its broadest context, not limited
to the definition to suspended solids and
BOD. They recognized the fact that
traditional methods of what was t_h_en.
called secondary treatment produced
a range of effluent quality of 50-90
percent reduction (2).
LAGOONS AND SECONDARY TREATMENT
For years the subject of lagoons has
been a topic for discussion. Numerous
authors have cited a gamut of research
needs. The first major meeting address-
ing the subject of lagoons (oxidation
ponds, etc.) was held in 1960. E. E.
Smallhorst of the Texas Department of
Health called for more knowledge of
ponds. He cited the problem of the algae
green color in effluents as being the
most pressing need followed by the need
to determine the sanitary quality of pond
effluents, and a definition of the
limiting factor for control of algae
laden effluents in a receiving body of
water (3). Referring to ponds in the
upper Midwest States, primarily North
Dakota, J. Svore and W. Van-Heuvelen
praised the merits of lagoons, but did
not classify ponds as conventional
secondary treatment (3). In the State of
North Dakota today, all treatment of
sewage is performed in lagoons with the
exception of one community. However,
there is a concern for effluent quality
since most of the systems in that state
are controlled discharge systems. In a
controlled discharge system, discharge is
allowed only a few times a year. The
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final cell is taken out of service and is
allowed to remain in a state of quies-
cence for a period of time. The algae
settle, then the operator discharges a
very high quality effluent. This tech-
nique is practiced in other northern
states.
Gulp stated that whenever ponds were
used for secondary treatment, it was an
exception to the general practice of
following conventional primary facilities
with conventional secondary units. D. P.
Green of Wyoming's Department of Public
Health did go on record that pond ef-
fluents produced an effluent equivalent
to the conventionally accepted methods of
secondary treatment (3).
Ponds were the topic of a second
international symposium in 1970. Middle-
ton and Bunch cited high concentrations
of suspended solids in effluents as one
of the major disadvantages (4). They
were concerned about the inability to
predict the quality of effluent from
ponds as confidently as one might predict
the effluent quality of more conventional
technology .
G. M. Barsom and D. W. Ryckman
analyzed pond performance with respect
to the requirements of the Water Quality
Act of 1965. Barsom noted that:
It is true that lagoons more
closely approach natural
purification than any other
treatment process; however,
what has not been fully
recognized is that the objec-
tives of natural purification
and waste treatment are differ-
ent. As discussed above, the
goal of natural purification is
to recycle pollutants. The
goal of waste treatment is to
remove pollutants. Oxidation
ponds, which emulate natural
purification, recycle rather
than remove pollutants.
This is the fundamental reason
why !i[j[O££s_aj^e_u_ri£b^._e_t_o_
aghj^gve acceptable effluent
quality and why lagoons should
not be considered equivalent to
The author went on to note that in
addition to quality failures, there
were aesthetic failures by lagoons which
could be grouped into the following: (1)
obnoxious hydrogen sulfide odors, (2)
malodorous algae blooms, (3) noxious
vegetative growth, (4) mosquito breeding,
(5) highly_c_plpred effluents, and (6)
septic sewage odors. He found that in
most cases studied, oxidation ponds did
not significantly enhance water quality
based upon reduction of suspended solids,
volatile solids, chemical oxygen demand,
nitrogen, and phosphorus.
In a later publication by Barsom, he
noted that "suggestions that chlorination
of effluent and the subsequent killings
of algae cells does not degrade stream
quality is unsupported." (6) He en-
couraged additional research on this
subject as well as on algae removal
systems. The report did include data on
suspended solids which indicated that
ponds would have great difficulty in
meeting the requirements of secondary
treatment as defined under the FWPCA
amendments of 1972. Barsom noted that
secondary treatment had traditionally
been equated to biological treatment of
wastewater (bacteria and microorganisms
breakdown complex organic pollutants
to more stable substances), and that
"lagoons had been considered secondary
treatment." Prior to the Act of 1972,
there was jio standard definition (in
terms of pollutant concentrations) of
secondary treatment although environ-
mental engineers used the term to denote
removal of dissolved organic materials as
well as suspended solids.
EFFECTS OF ALGAE ON
RECEIVING STREAMS
While many authors reported on the
performance of ponds and attempted
to relate that to design criteria, few
included suspended solids removal
efficiency data. In addition to Middle-
ton and Bunch, D. L. King, R. C. Bain,
and others cautioned against the probable
impact of suspended solids (namely,
algae) on receiving streams. King et al.
(7) reported that algae-laden effluents
can significantly influence the condition
of the receiving stream; in fact, the
receiving stream may become a part of the
total waste treatment system. Bain et
al. (8) reported that the oxygen demand
loading from the pond they investigated
exceeded that of the river upstream of
the plant. These reports and a report for
the EPA by Hill and Shindala (9) show
that the 8005 value of an algal-laden
lagoon effluent is often only 20-30
percent of the BOD26 and BODo0 values
recorded. However, in many instances the
rate of die-off and decay of the algae in
the receiving stream has been slow
enough to blend in with the transforma-
tions of other naturally occurring
plant substances (leaves from trees,
aquatic plants, shore plants) and does
not create a nuisance condition in the
receiving stream. Thus in many cases,
there is no steep increase in oxygen
demand below the lagoon effluent nor
are there obnoxious odors. This fact has
been recognized by the EPA in amending
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the suspended solids regulation concern-
ing the effluent limitations for small
publicly owned lagoon treatment systems.
REVISION OF SECONDARY
TREATMENT STANDARDS
The definition of secondary treat-
ment for federal regulation of munici-
pal wastewater treatment plant effluents
has been modified because of a continuing
dialog between the EPA and state water
pollution control agencies and re-
searchers. This will be covered in more
detail in the next paper of this sympo-
sium. The Federal Register, Vol. 41, No.
144, Monday, July 26, 197,6, contains
amendments pertaining to effluent values
for pH and deletion of fecal coliform
bacteria limitations from the definition
of secondary treatment. The amendment
allowing less stringent suspended solids
limitations for wastewater treatment
ponds is found in the Federal Register,
Vol. 42, No. 195, Friday, October 7,
1977. The relaxation of the suspended
solids limitations was based partly on
evidence that in many instances release
of live algae into receiving waters did
not appear to create odors or adversely
affect the receiving stream. It was also
partly based on the decision that
costs of adding algae removal devices or
replacement of lagoon systems with
other types of wastewater treatment
plants would be too costly and take
too much time to meet the 1977 deadline.
States may still impose more stringent
suspended solids limitations on treatment
plants discharging to water quality
limited streams.
DISINFECTION OF LAGOON
EFFLUENTS
The removal of enteric bacteria and
pathogens in wastewater lagoon systems
has been well documented in the litera-
ture. Okun (10) reported 99.99 percent
reduction of coliforms in each of five
experimental ponds loaded at up to 100
pounds of BOD per acre per day. Geld-
reich et al. (11) in a study of raw
sewage and effluent from a waste stabili-
zation pond located at a state prison
dairy farm, reported a reduction in
coliform bacterial density from a low of
85.9 percent in the winter to a high of
94.4 percent in the autumn. Fecal
coliform reductions were greater than
87-9 percent, while reductions of fecal
streptococci were 97.4 percent or more.
Coetzee and Fourie (12) reported a 99.98
percent reduction of _E. coli in waste-
water lagoons while Drews (13) found that
1• £°11 was reduced 99.6 percent in
summer and 96.8 percent in the winter.
Amin and Ganapati (14) reviewed some of
the theories proposed for the bacterial
reduction such as the production of
materials toxic to the bacteria, germi-
cidal effects of sunlight, sedimentation,
and competition for nutrients. Using a
laboratory-scaled lagoon, they also
correlated the reduction of the enteric
bacteria with biochemical changes occur-
ring as the lagoon treatment of the
wastewater progressed. The growth of the
algae, Chlorella, and production of extra
cellular fatty acids appeared to have an
antibacterial effect. Gann et al.
(15) found coliform reduction to be
closely associated with BOD removal
indicating that the coliforms may have
been removed because of their inability
to compete successfully for nutrients.
Coetzee and Fourie (12) feel that because
of the ease of elimination of E_. coli in
stabilization ponds that it may not be an
infallible indicator of pathogenic
organisms in wastewater lagoon effluents.
Malchow-Moller et .al. (16) considered
that Streptococcus faecalis and Clostri-
dum welchii were more reliable indicators
of pathogens in such lagoon effluents.
Although fewer tests for pathogens
have been conducted in lagoon system
influents and effluents than tests for
the"indicator organisms, most results
show a die-away of the pathogens.
Coetzee and Fourie (12) found the total
reduction of Salmonella typhi in the
effluent from two stabilization ponds
operated in series with a detention time
of 20 days to be 99.5 percent at a
time when the reduction of E_. coli was
99.98 percent. Using £5 JLa£ _L°-H.2.£i!H£
juirjMJSi and Serratia marcesens as test
organisms, Conely et al. ~T~1 7) found
an almost complete die-off of these
organisms in the upper aerobic zone of
a lagoon in 36 to 48 hours. Christie
(18) found that field lagoons reduced
the titre levels of polio virus from
105 to less than 103 units per milliliter.
Little, Carroll, and Gentry (19) and
Slanetz et al. (20) indicate that series
operation of lagoon systems produce
better bacterial quality effluents than
do single-celled systems. Slanetz (20)
showed that when the ponds were operated
in a series of three or four ponds, very
few viable indicator bacteria remained in
the effluents from the last lagoon in
the series when the temperature of the
lagoons ranged from 10 to 26°C. Counts
as low as 2 per milliliter or less
were obtained for coliforms, fecal
coliforms, and fecal streptococci.
Salmonella could be detected in only 1
out of 24 effluent samples from the third
or fourth lagoon in the series during
the summer. However, enteric viruses
were isolated from a number of these
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effluent samples. The percentage sur-
vival of coliforms, fecal conforms,
and fecal streptococci was much higher
during the winter when the temperature
in the lagoons ranged from 1 to 10°C.
The isolation of enteric pathogens
was also more frequent during the winter
from the lagoon effluents. Joshi,
Parhad, and Rao (21) tested the perfor-
mance of two lagoon systems located
at Nagpur, India, with respect to the
reduction of S_a JLmoji ei_l_l_a, coliforms,
£_. coli, and fecal streptococci. Sal-
monella were not completely eliminated
from the effluent of a two-celled lagoon
that had submerged connections between
the cells, while none were found in 1
liter samples of effluent from the third
cell of a three-celled lagoon with the
cells connected by a surface overflow
arrangement. The authors concluded that
the number of cells and interconnecting
arrangements are important design fea-
tures to be considered as well as loading
rates and detention times for lagoon
systems. Using a six-celled lagoon system
near Oklahoma City, Oklahoma, Carpenter
et al. (22) showed that no pathogens were
found in the wastewater beyond the
fir'st two lagoon cells in series or in
any of the 179 fish sampled from those
grown in cells three to six.
Marais (23) presents a consolidated
theory for a kinetic model for the
reduction of fecal bacteria in stabili-
zation ponds incorporating the effect
of temperature on the specific death rate
as well as discussing effects of mixing,
anaerobic conditions, recycling of
effluent, and the relationship between a
single pond, a series of ponds, and batch
conditions. The rate constant K (die-off
rate) is very sensitive to temperature
and is approximately related to K = 2.6
(1.19)T~2°, (T°C). It is presumed in
this relationship that the ponds are
mixed and aerobic or facultative and is
valid between 5 to 21°C. Above 21°C,
with low wind velocities, periods of
stratification occur causing the lower
liquid depth of the pond to be anaerobic.
There is a decline in the K value under
anaerobic conditions; the reduction
of fecal organisms is sharply reduced.
When winter temperatures are very
low, the K is very small and series
operation will yield only relatively
minor improvement over single pond
operation.
Sobsey and Cooper (24) found that in
a 1 ga 1-bacteria 1 treatment systems
both virus adsorption to solids and virus
inactivation due to microbial activity
play a role in reducing the enteric virus
concentration in wastewater. In labora-
tory cultures the growth of the alga
Scedesmus quadricauda and the bacterium
Ba.cillus~megaterium in sterile sewage had
detrimental effect on polio virus sur-
vival, whereas the growth of heterogenous
populations of stabilization pond bac-
teria in the same medium resulted in
substantial virus inactivation.
Horn (25) showed that selective
chlorination can be achieved for lagoon
effluents under controlled conditions,
whereby coliforms are destroyed, yet
leaving the algae essentially intact.
Control of time of reaction and con-
centration of chlorine is essential,
however, excessive chlorine can release
materials from algal cells and increase
the effluent BOD.
Melmed (26) reported that gamma
radiation or radiation plus chlorine
could be used for the disinfection of an
effluent from a maturation pond.
HEAVY METALS AND ALGAE
The question has been raised as to
whether or not the algae growing in
wastewater lagoons can carry significant
amounts of harmful heavy metals through
the treatment process and into the
effluent to cause subsequent problems in
the receiving stream. Like other plants,
algae can adsorb and absorb many miner-
als; they have a requirement for small
concentrations of many metals needed for
their enzyme systems. O'Kelly (27) gives
an excellent review of the inorganic
nutrients of algae covering 16 elements.
He includes information concerning
accumulation of some elements by certain
algae and information concerning toxicity
effects towards algae. There are dif-
ferent effects at the same concentration
of metal for different algae and the ef-
fects are conditioned by other factors in
the growth and nutrition of the algae.
It is often uncertain, as Ramani
(28) pointed out in reporting on the
removal of chromium in the series oper-
ated Napa, California, lagoon system,
as to whether the metal was adsorbed,
assimulated, or precipitated to the
bottom of the lagoon cells. Reed et al.
(29) show that no excessive concentra-
tions of heavy metals occur in forage
grasses receiving lagoon effluents at
sites where the effluents have been used
for irrigation for periods ranging from
10 to 76 years.
Andrew et al. (30) showed that a
fresh water alga, Chara bra
-------
the algae of a waste pond which has been
receiving Pu processing wastes for
approximately 30 years. Hart and Scaife
(32) reported the bioaccumu1 ation
of cadmium in Chlorella pyrenoidosa. The
organism had the ability to accumulate
large concentrations of Cd before showing
adverse effects, such as decreased CC>2
fixation or decreased 03 evolution.
Wixson (33) showed how the accumulation
of metals by algae could be used in the
purification of the effluent from Pb/Zn
mining and smelting operations.
A number of the heavy metals,
however, have an inhibitory or toxic
effect on many of the algae. Greene et
al. (31*) and Miller et al. (35) describe
the toxicity of zinc to the green alga
S.^l.f.BiLs. JiUM!" £5E£l.c_.o.Jl.n..u. JiHE a n ^ also
demonstrated that zinc levels in the
Spokane River had an effect on limiting
the amount of algal growth that occurred.
Hassall (36) studied the effects of
copper on Chlorella vulgaris and suggests
that the toxic effect of the copper may
be its effect on the phosphorus metabo-
lism of the growing cells or that the
copper renders the cell permeable to
solutes. Copper has frequently been used
as a fungicide or as an algicide.
TASTES AND ODORS FROM ALGAE
An excellent review of the different
types of tastes and odors that are
associated with algae in water is given
by Palmer (37). Typical descriptions
of some of the odors encountered are
aromatic, fishy, grassy, musty, or
earthy, and pig-pen or septic. Tables
are presented by Palmer showing the
type of odor and taste associated with a
number of algal genera from a large
variety of algal groups.
Jenkins et al. (38) identified by
gas chromatographic techniques several
odorous sulfur compounds including methyl
mercaptan, dimethyl sulfide, isobutyl
mercaptan, and n-butyl mercaptan in
cultures of blue-green algae. Most of
these compounds arose from bacterial
putrefaction of the blue-green algal
cells. However, the organism Microcystis
flos-aquae was shown to produce isopropyl
mercaptan during periods of active
growth. Safferman et al. (39) found that
Symploca muscorum, a blue-green alga,
produced an earthy-smelling metabolite at
an estimated concentration of 0.6 mg/1
of culture medium. The substance was
identified as Geosmin by a direct com-
parison to an actinomycete produced
standard. Medsker et al. (40) proved
that there was no actinomycete contamina-
tion of the S_. muscorum culture obtained
from R. S. Safferman. The compound
Geosmin, Ci2H22°> was shown to be a
dimethyl substituted, saturated, two-ring
tert-alcohol. The growth of the blue-
green alga Oscillatoria in fish ponds in
Israel caused an off-flavor in carp from
the fish pond (41). Lovell and Scakey
(42) showed that channel catfish aquired
the distinct earthy-musty flavor associ-
ated with Geosmin when grown in tanks
containing dense masses of either symplo-
ca muscorum or Oscillatoria tenuis. The
TTsh acquired the flavor within 2 days;
flavor intensity reached a maximum at 10
day.
Silvey et al. (43) discussed some of
the control methods, such as forced
aeration and recirculation in impound-
ments to prevent stratification and
growth of the odor producing blue-green
algae. Treatment with chlorine and
use of activated carbon does help to
minimize or remove Geosmin from the
water. A bacterial oxidation of Geosmin
is described by Narayan and Nunez
(44) that may also be used to reduce the
odor problem.
AQUATIC TOXICITY FROM ALGAE
Certain algae may produce substances
that can elicit a variety of clinical
responses from fish, animals, and man.
The clinical manifestations may range
from digestive disturbances (vomiting and
diarrhea) to organ damage, neuromuscular
disfunction, and death. The most common
groups causing toxic problems are the
blue-green algae in fresh waters and
flagellates or chrysomonads in marine
waters. The marine forms are the pro-
ducers of an alkaloid that is concen-
trated in shellfish (it is nonpoisonous
to the shellfish) and is the paralytic
shellfish poison that has caused numerous
human deaths. The blue-green algae have
caused numerous fish kills and deaths
of many types of animals. Schwimmer and
Schwimmer (45) present a masterly
review of the medical problems caused by
algae. They reference over 250 indi-
vidual research papers covering animal
intoxications from algal blooms (blue-
green algae), experimental testing of
bloom material on test animals, and the
toxic manifestations following the
experimental administration of these
naturally occurring toxic fresh water
algae, toxic manifestations following
experimental administration of laboratory
cultured algae, effects on fish in fresh
and salt waters, and effects on humans.
HEALTH EFFECTS OF ALGAE
The toxic effects of the blue-green
algae have been studied extensively.
Gorham (46,4?) reports on laboratory
studies on the toxins produced by
-------
blue-green algae. At least two toxins
produced by strains of M_i££££ jr s-_tjL s>
aeurginosa and Aj]_a]>_ejia f los-aquae are
r e s p o ns i b~l e for acute poisonings of
animals. Bacteria associated with the
algae also produced toxins respon-
sible for less acute poisonings. Micro-
cystis fast-death factor is a cyclic
polypeptide of moderate toxicity which
kills livestock and other animals but
not waterfowl. The structure of Anabena
very-fast-death factor was not eluci-
dated. It killed a variety of animals,
including waterfowl. Maloney and Games
(48) showed that the fast-death factor
toxic from Microcystis while lethal for
mice had no effect on three species of
fish or Daphnia. Aziz (49) isolated the
toxin in a non-dialyzable fraction of the
lysate from whole cells of Microcystis
and showed that this material caused
diarrhea in the litigated small intesti-
nal loops in guinea pigs. Carmichael et
al. (50) showed that the main effect of a
toxin isolated from bacteria-free
lyophilized suspensions of AH^^H^
f.Lc:_s^a..q.u.a_.e_ was production of a sub-
stantial" postsynaptic depolarizing
neuromuscular blockage; the animals died
as a result of respiratory arrest.
In the review by Schwimmer and
Schwimmer (45), references are given
to work by Dillenberg (51), Hayami and
Shino (52,53,54), and McDowell (55,56)
that show that green algae can also be
causative agents of human gastrointesti-
nal disorders besides those caused by
blue-green algae. Bernstein and Saffer-
man (57,58,59,60) in a series of papers
showed that animals and man can have
allergic responses to green algae. This
was shown to be elicitated by skin
sensitivity and by nasal challenge with
aerosolized extracts of Chlorella vul-
garis. The authors showed that viable
green algae occurred in house dust. Of
37 patients exhibiting allergic responses
to a 1:10,000 dilution of house dust, 22
showed positive reactions to one or more
of the algal extracts diluted 1:10,000
and 5 to extracts diluted 1:1,000.
Thus, house dust may be a likely source
of human exposure and sensitization
to many varieties of algae, which may
give rise to clinical allergic problems.
EPA RESEARCH PROGRAM
Recent literature (61,62,63,64)
continues to cite the problems of ponds
with the control of algae as one of the
major problems. The most frequently
cited problems associated with oxidation
ponds over the years had been odors
and organic matter in the effluent. With
the increased concern over the ability of
oxidation ponds to meet the effluent
limitations, concerns were more sharply
focused on the solids, nutrients, and
bacteria in the effluent. All of these
problems and concerns can be related to
the drainage, maintenance, and control of
the biological reactions of the ponds.
The general research needs related
to the use of oxidation ponds as a
wastewater treatment alternative are and
continue to be:
-Design and operation as related to
effluent quality
-Seasonal and climatic performance
variations
-Cost effectiveness to delineate
where supplemental aeration
equipment or use of an aerated
lagoon is preferable
-Control of excessive solids in the
effluent
-The type of nutrient control that
may be effective
-Disinfection needs and appropriate
methodology
-Need for supplemental nutrients
with industrial wastes
-Land disposal methodology for
oxidation pond discharge
-Protection of groundwater quality
R&D PROGRAM OBJECTIVES
The Environmental Protection Agency
embarked upon a research and development
program designed to identify design
criteria and technology to upgrade the
effluent quality of oxidation ponds. The
specific research objectives identified
by EPA in conjunction with state and
local officials were:
a. Low cost suspended solids
removal processes
b. Design guidelines for discharg-
ing oxidation pond effluent to
the land
c. Disinfection guidelines and
demonstration of applicable
disinfection methods
d. Development and demonstration of
nutrient control technology
e. Evaluation of utilizing the
separated suspended solids in
the pond effluent as a useful
product, such as a supplement
for animal feed
f. Relationship of pond design to
an upgrading of pond performance
(performance evaluations of
facultative and aerobic systems)
These needs are applicable to ponds
used for the treatment of both municipal
and industrial wastewaters.
10
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R&D PROGRAM STATUS
A specific research and development
program related to the performance
of oxidation ponds was established.
Several large scale projects were funded
with preliminary results reported at
other symposia and the full results
will be presented in greater detail at
this meeting.
Under design, construction and/or
operation are intermittent sand-filters,
submerged rock filters, chemical addition
technology, phase-isolation systems,
and systems applying effluent to the
land. Results of these studies will
also be presented at this symposium.
PRELIMINARY COSTS
The results from the studies to date
have permitted an order of magnitude
estimate of the costs of upgrading
oxidation ponds. To upgrade all known
existing oxidation ponds in the country
would cost about $2 billion, whereas
replacing all ponds with mechanical
plants was estimated to cost about $5
billion. More specifically, the cost of
add-on devices such as slow-sand inter-
mittent and slow-rock filters, and
chemical addition was estimated as about
$1000/1000 gallons compared to about
$2000-$2900/1000 gallons for conversion
to a mechanical plant of the same capaci-
ty (about 0.2 mgd). Oxidation ponds can
be upgraded by any one of several add-on
devices or by employing more land to
facilitate conversion to a controlled
discharge system, whichever is the more
cost-effective alternative. Based upon
the recent research results, it appears
that upgrading oxidation ponds is a
viable alternative.
SUMMARY
We may summarize lagoon treatment
systems without algal removal or efforts
to minimize the amount of algae in the
effluent as having the follow-
ing effects:
1. Ultimate oxygen demand of the
receiving water will be high if the
algae accumulate in sludge banks or
settle out in basins. Approximately
2/3 of the algal mass may decay. This
could lead to a low DO in the receiving
water.
2. Enteric indicators of fecal
pollution and pathogens decrease in
the treatment process. Differences in
temperature, detention time, and short
circuiting in some lagoon systems lead to
all pathogens being removed without
the necessity of the use of chlorine or
other disinfectants in some cases
and not in others. Algae in the ef-
fluents can interfere with the efficiency
of the disinfection process.
3. Most small towns have little in
the way of heavy metal contamination
of the raw wastewater. In a few in-
dustrial lagoon systems described in
the literature, the heavy metals pre-
cipitated in the anaerobic layers at the
bottom of the lagoon cells.
4. Extensive masses of algae can
lead to taste and odor problems. Release
of algae from lagoon effluents and
subsequent decay can release nutrients
(nitrogen and phosphorus) that were
removed from the wastewater by the growth
of the algae in the wastewater lagoon
cells. These nutrients may aid in the
development of the • obnoxious blue-green
algae. Poor management of the wastewater
lagoon systems may allow extensive
growths of blue-greens directly in the
lagoon system, creating odor problems.
5. Extensive growths of algae may
cause allergies or other clinical
problems to animals or men that come into
c-lose contact with the masses of algae by
swimming in the receiving water, in-
gesting the water, or breathing an
aerosol of these algae. This is es-
pecially a problem where there are
large masses of decaying algae.
Methods have been developed to
economically prevent algae from reaching
the effluent or removing the algae from
the effluent in a polishing system
that can be used by small communities
where operators are only infrequently
at the waste treatment plants. With
proper design, operation and algae
removal processes, wastewater lagoon
systems are one of the most reliable,
least costly, and most effective waste
treatment systems.
REFERENCES
1. Secondary Treatment Information
40 CFR Part 133, Federal Register
22298, August 17, 1973.
2. Legislative History of the Water
Pollution Control Act Amendments
of 1972. Serial No. 93-1, Vols. 1
and 2, Congressional Research
Service of the Library of Congress.
3. Waste Stabilization Lagoons. Pro-
ceedings of a Symposium at Kansas
City, Missouri, August 1-5, I960.
U.S. Dept. of HEW, Public Health
Service Publication No. 872,
Aug. 1961.
11
-------
4. Middleton, F. M., and R. L. Bunch. 13.
Challenge for Wastewater Lagoons.
Second International Symposium for
Waste Treatment Lagoons, June 23-25,
1970, Kansas City, Missouri.
Lawrence, Kansas, Ross E. McKinney
(editor), University of Kansas, p 11.
364-366-
5. Barsotn, G. M. and D. W. Ryckman.
Evaluation of Lagoon Performance 15.
in Light of 1965 Water Quality Act.
Second International Symposium
for Waste Treatment Lagoons, June
23-25, 1970, Kansas City, Missouri.
Lawrence, Kansas, Ross E. McKinney 16.
(editor), University of Kansas. p
63-80.
6. Barsom, G. Lagoon Performance and
the State of Lagoon Technology. 17.
Environmental Protection Technology
Series EPA-R2-73-144 , June 1973-
7. King, D. L., A. J. Tolmsoff, and
J. J. Atherton. Effect of Lagoon
Effluent on Receiving Stream. 18.
Second International Symposium for
Waste Treatment Lagoons, June 23-25,
1970, Kansas City, Missouri.
Lawrence, Kansas, Ross E. McKinney 19.
(editor) , University of Kansas. p
159-167.
8. Bain, R. C. Jr., P. L. McCarty,
J. A. Robertson and W. H. Pierce.
Effects of an Oxidation Pond Ef-
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Joaquin River Estuary. Second
International Symposium for Waste 20.
Treatment Lagoons, June 23-25, 1970,
Kansas City, Missouri. Lawrence,
Kansas, Ross E. McKinney (editor),
University of Kansas. p 180-186.
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Lagoon. Environmental Protection
Technology Series, EPA-600/2-77-109,
August 1977.
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553, 1962.
11. Geldreich, E. E., H. F. Clark,
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Drews, R. J. L. C. Field studies
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Biochemical changes in oxidation
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Gann, J. D., R. E. Collier, and C.
H. Laurence. Aerobic bacteriology
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Conely, J. E.
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Christie, A. E. Virus reduction
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Un iversity
Slanetz, L. W., C. H. Bartley,
T. G. Metcalf, and R. Nesman.
Survival of enteric bacteria and
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Second International Symposium for
Waste Treatment Lagoons, June 23-25,
1970, Kansas City, Missouri.
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132-141.
Joshi, S. R., N. M. Parhad, and N.
V. Rao. Elimination of Salmonella
in stabilization ponds. Water
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Carpenter, L. R., H. K. Malone,
A. F. Roy, A. L. Mitchum, H. E.
Beauchamp, and M. S. Coleman. The
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sewage and sewage-grown fish.
Wastewater Use in the Production of
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Series EPA 660/2-74-041, June
1974.
Marais. G.v.R. Fecal bacterial
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JAS CE 100: No. EE1, 119-139, Feb
1974.
12
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24. Sobsey, M. D., and R. C. Cooper.
Enteric virus survival in algal-
bacterial wastewater treatment
systems - 1. Water Research, 7:
669-685, 1973.
25. Horn, L. W. Chlorination of waste
pond effluents. Second Internation-
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Ross E. McKinney (editor), Univer-
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26. Melmed, L. N. Disinfection of
municipal waste water with gamma
radiation water S. A. 2(3): 131-
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27. O'Kelly, J. C. Inorganic nutri-
ents. Chapt. 22, p 610-635.
Algal Physiology and Biochemistry
Botanical Monographs Vol. 10,
University of Calif. Press. 1974.
28. Ramani, R. Design criteria for
polishing ponds. Paper presented
at Symposium "Ponds as a Wastewater
Treatment Alternative" University
of Texas, Austin, Texas, July 23,
1975.
29. Reed, S. C., H. McKim, R. Sletten,
and A. Palazzo. Pretreatment
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of wastewaters. Paper presented
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Environmental Engineering, Research
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of Florida, Gainesville, Florida.
July 20-23, 1975.
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Scarpino. The uptake and distribu-
tion of manganese-54 by £h££^
]>£.§ HHil in a freshwater system.
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31. Emery, R. M., D. C. Klopfer, T.
R. Garland, and R. C. Weimer.
Ecological behavior of plutonium and
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Report 1975 BNWL-SA 5346 and BNWL-SA
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32. Hart, B. A., and B. D. Scaife.
Toxicity and bioaccumulat ion of
cadmium in Chlorella pyrenoidosa.
Environ. Res. 14(3): 401-413. 1977.
33. Wixson, B. G. Industrial treat-
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area. Proc. Ind. Waste Conf..Pur-
due, 1975, 30: 1173-1180. 1977.
34. Greene, J. C., W. E. Miller, T.
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of zinc to the green alga Selenas-
trum capricornutum as a function of
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39.
40.
41.
42.
43.
44.
phosphorous or ionic strength.
Proceedings Biostimu1 ation and
Nutrient Assessment Workshop, Oct.
16-17, 1973. EPA 660/3-75-034, June
1975, p 28-43.
Miller, W. E., J. C. Greene, T.
Shiroyama, and E. Merwin. The use
of algal assays to determine effects
of waste discharges in the Spokane
river system. Proceedings Biostimu-
lation and Nutrient Assessment
Workshop, Oct. 16-17, 1973. EPA
660/3-75-034, June 1975, p 113-131.
Hassall, K. A. Uptake of copper
and its physiological effects on
£hl_o.r.e_l.l.a X^iS-3.!!..?:.?. • Physiologia
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Palmer, C. M. Algae in water sup-
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Publication No. 657. 1957. Chapt.
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Jenkins, D., L. L. Medsker, and
J. F. Thomas. Odorous compounds
in natural waters. Some sulfur
compounds associated with blue-green
algae. Environ. Sci. & Technol., 1:
731-735. 1967.
Safferman, R. S., A. A. Rosen, C.
I. Mashini, and M. E. Morris.
Earthy-smelling substance from a
blue-green algae. Environ. Sci. &
Technol., 1: 429-431. 1967.
Medsker, L. L., D. Jenkins, and
J. F. Thomas. Odorous compounds
in natural waters. An earthy-
smelling compound associated with
blue-green algae and actinomycetes.
Environ. Sci. & Technol., 2: 461-464.
1968.
Aschner, M., C. Laventer, and I.
Chorin-Kirsch. Off flavor in carp
from fishponds in the coastal plain
and the galil. Bamidgh, Bulletin
of Fish Culture in Israel 19(1):
23-25, 1967.
Lovell, R. T., and L. A. Scakey.
Absorption b'y channel catfish of
earthy-musty flavor compounds synthe-
sized by cultures of blue-green
algae. Trans. Amer. Fisheries Soc.,
102: 774-777. 1973-
Silvey, J. K., D. E. Henly, and
T. T. Wyatt. Planktonic blue-green
algae: growth and odor-production
studies. JAWWA, 64: 35-39. 1972.
Narayan, L. V.
III. Biological
and bacterial
taste-and-odor
and W. J. Nunez
control: isolation
oxidation of the
compound Geosmin,
JAWWA, 66: 532-536. 1974.
13
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45.
46.
47.
48.
49.
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54.
Sc hw immer, M. and D
Medical aspects of
Chapter 15, p 279-358.
and the Environment.
University Press. 1968.
Sc hw immer.
phycology.
Algae, Man,
Syracuse
Gorham, P. R. Laboratory studies
on the toxins produced by water-
blooms of blue-green algae.
Amer. J. Public Health, 52: 2100-
2105. 1962.
Gorham, P. R. Toxic algae. p
307-336 in Algae and Man. Plenum
Press N.Y. 1964.
Maloney, T. E., and R. A. Carnes
Toxicity of a Microcystis waterbloom
from Ohio pond. Ohio J. Sci.,
66(5): 514-517. 1966.
Aziz, K. M. S. Diarrhea toxin ob-
tained from a water bloom producing
species of Hi^Jlo^y^t^ aeurginosa
Kutzing. Science, 18~3= 120TP1207-
1974.
Carmichael, W. W., D. F. Biggs,
and P. R. Gorham. Toxicology and
pharmalcological action of Anabena
flos-aquae toxin. Science, 187:
rr~1975.
51. Dillenberg, H. 0. Toxic
bloom in Saskatchewan, 1959-
Med. Assoc. J., 83: 1151.
w ater-
Canad.
52. Hayami, H., and K. Shino. Nutri-
tional studies on decolourized
Chlorella (part 1). Growth experi-
ments of rats and the digestability
of a diet containing 19 percent of
decolourized Chlorella. Ann. Rept.
National Ins~t~Nutrition, Tokyo.
1958.
53- Hayami, H., K. Shino, K. Morimoto,
T. Okano, and S. Yamamato. Studies
on the utilization of Chlorella as a
i . wnouu, emu kj . x aiijanid uu . ouuuxco
on the utilization of Chlorella as a
source of food. Human experiments
on the rate of absorption of protein
nf blanched Chlorella. Ann.
Inst. Nutrition,
Rept
1960
Nat.
Ann.
Hayami, H., K. Shino, K. Morimoto,
and M. Tsuchida. Studies on the
utilization of Chlorella as a source
of food (Part 10). Human experi-
ments on the rate of digestion of
protein of C_hlore±la dried at a
low temperature. Ann. Rept. Nat.
Inst. Nutrition, Tokyo. I960.
55. McDowell, M.E., and G.A. Levelille.
Feeding Experiments with Algae.
Federation Proc., 22: 1431. 1963.
56. McDowell, M. E., R. C. Powell,
E. M. Nevels, J. N. Sellars, and N.
F. Witt. Algae feeding in humans:
Acceptability, digestability, and
toxicity. 44th Ann. Meeting Fed.
Amer. Soc. Exp. Biol. , Chicago I960
Abstracts 19 (11): 319.
S. Safferman.
skin and bronchial
algae. Journal of
166-173. 1966.
57. Bernstein,
58.
59.
60.
, L. , and
Sensitivity of
mucosa to green
Allergy
j gji \*\*t.
38(3)
Bernstein, L., G. V. Villacorte,
and R. S. Saffermant Imunologic
responses of experimental animals to
green algae. Journal of Allergy,
43(4): 191-199. 1969-
Bernstein, L., and R. S. Safferman.
Viable algae in house dust. Nature,
227: 851-852. 1970.
Bernstein, L., and R. S. Safferman.
Clinical sensitivity to green
algae demonstrated by nasal chal-
lenge and in vitro tests of immedi-
ate hypersensitivity. Journal of
Allergy and Clinical Immunology
5KD: 22-28. 1973-
61. Waste Treatment Lagoons - State-
of-the-Art. Missouri Basin Engi-
neering Health Council, EPA Water
Pollution Control Research #17090
EXH. July 1971.
62. Loehr, R. C., and D. J. Ehreth.
Oxidation ponds--research needs to
meet effluent limitations. Univ. of
Texas Symposia. Ponds as a Waste-
water Treatment Alternative.
Austin, Texas. July 1975.
63. Middlebrooks, E. J., D. H. Falken-
borg, R. F. Lewis, and D. J.
Ehreth. Editors. Upgrading waste-
water stabilization ponds to meet
new discharge standards. Utah State
University, Logan, Utah. Nov.
1974.
64. Lewis, R. F. Limitations of
lagoon system and review of EPA's
research and development lagoon
upgrading program. Second National
Conference on Environmental Engi-
neering Research, Development and
Design, Univ. of Florida. July
1975.
14
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RECENT AMENDMENTS TO SECONDARY TREATMENT REGULATIONS
FOR SUSPENDED SOLIDS IN LAGOONS
Stanley M. Smith*
Amendments to the Secondary Treat-
ment Regulations (40 CFR Part 133.103)
which were promulgated by the Environ-
mental Protection Agency on September 28,
1977, and which became effective on
November 7, 1977, allow less stringent
suspended solids limitations for waste-
water treatment ponds for small munici-
palities. The amended regulations and
the official notice of this action are
contained in the October 7, 1977, Federal
Register, pages 54664 through 54666.
Modification of the suspended solids
limitations is not a blanket action
applicable to all wastewater treatment
ponds. Instead, modifications are allow-
able on a case-by-case basis for pond
systems in which waste stabilization
ponds are the sole process used for
secondary treatment, where the maximum
facility design capacity is two million
gallons per day or less and where opera-
tional data indicate that a monthly
average suspended solids concentration of
36 nisg71 cannot be achieved. In some
states the amended regulations are
already being implemented, in some states
the revised suspended solids values which
will be allowed are still under devel-
opment, and in some states there are
no plans to allow any variance from the
suspended solids values specified by the
secondary treatment regulations.
As most of you are aware, Public Law
92-500--the Federal Water Pollution
Control Act—became law on October 18,
1972. This Act gave the Environmental
Protection Agency 60 days to define
secondary treatment, and it required all
Publicly Owned Treatment Works (POTW's)
to achieve the effluent quality obtain-
able with secondary treatment by July 1 ,
1977. You are also probably aware that
•Stanley M. Smith is Chief, Control
Technology Branch, Environmental Protec-
tion Agency, Region VIII.
many POTW's were unable to meet the July
1, 1977, deadline fpr secondary treat-
ment. In some cases this was because
federal financial assistance was not
available and the needed facilities could
not be constructed in time, and in other
cases it was because the facilities
that were built could not meet the
specified effluent quality.
From the beginning there was much
concern as to whether waste stabiliza-
tion pond systems could meet the second-
ary requirements, particularly for
suspended solids concentrations. How-
ever, the agency had missed its 60 day
statutory deadline and it was under
considerable pressure to promulgate the
secondary treatment regulations when this
action was finally accomplished and
published in the Federal Register in
August 1973. As you know, the initial
secondary treatment regulations provided
for meeting the following basic effluent
limitations:
BODc and Suspended Solids—
3D mg/1 (monthly average)
BODc and Suspended Solids--
45 mg/1 (weekly average)
Fecal coliform--200 per 100 ml
(30 day geometric mean)
Fecal coliform—400 per 100 ml
(7 day geometric mean)
pH—6.0 to 9.0
Almost immediately after the regula-
tions were adopted, the agency held
several meetings to further evaluate the
waste stabilization lagoon problem.
The agency did not want to drive conven-
tional wastewater treatment lagoon
systems out-of-use as secondary treatment
devices, yet, there was mixed opinion as
to whether or not conventional two and
three cell systems could meet secondary
requirements on a consistent basis. In
March 1974, it was decided to publish a
Technical Bulletin on wastewater treat-
ment ponds as additional guidance rela-
tive to the use of lagoon systems in the
construction grants program.
15
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For flow-through photosynthetic
ponds, the Bulletin indicated that
grants would only be made where there was
reasonable assurance of satisfactory
performance. A determination of satisfac-
tory performance could be based upon a
similar pond system in a similar environ-
ment or the performance of a pilot
project. In addition, the Bulletin
called for the facility plans for
pond systems to include discussions
of actions to be taken if upgrading was
determined to be necessary after the
system was placed in operation.
In early 1975, EPA began discussing
possible revisions of the secondary
treatment regulations. On July 26, 1976,
the first set of modifications of
the secondary treatment regulations was
adopted. However, at this time there
was no adjustment of the suspended solids
requirements. The first set of modifica-
tions removed the effluent limitations
for fecal coliform organisms, and it
provided for modifications of the ef-
fluent values for pH when due to photo-
synthetic activity not caused by in-
organic chemicals added to the wastewater
or chemicals from industrial sources.
Subsequently on September 2, 1976, a
second modification of the secondary
treatment regulations was proposed which
would allow relaxation of the suspended
solids limitations for certain lagoon
systems of small communities. As men-
tioned earlier, this second modification
was adopted and became effective on
November 7, 1977.
The latest change in the secondary
treatment regulations reflects a desire
on the part of the Environmental Protec-
tion Agency to allow waste stabilization
pond systems to continue in use as viable
secondary treatment processes without the
need for extensive upgrading to meet
suspended solids limitations. In short,
the agency wants small communities to be
able to continue to take advantage of the
low construction cost and the less
complex operation and maintenance that is
possible with the use of pond systems
as secondary treatment devices. Where
higher degrees of treatment are needed
to meet water quality standards or other
considerations, ponds can also continue
to be used effectively in many situations
with various upgrading techniques that
have been developed through recent
research and demonstration projects.
What is the significance of the
new regulations and what are the con-
ditions that are attached to their
use? First, it should be recognized
that Section 510 of the Clean Water
Act gives any state the right to require
effluent limitations more stringent
than federal requirements. Therefore,
those states which do not choose to
allow relaxed effluent limitations
for suspended solids in lagoon systems
have every right to maintain more strict
requirements.
The regulations also apply only to
Publicly Owned Treatment Works and not
to industrial lagoon systems.
As indicated earlier, the relaxed
effluent limitations are to be applied
only on a case-by-case basis to pond
systems which meet standards for good
design but which cannot otherwise meet
secondary treatment requirements for
suspended solids. The relaxed standards
apply to pond systems where ponds are
the only means of secondary treatment
and only to pond systems where the
maximum facility design capacity is 2 mgd
or less. While- the secondary require-
ments for fecal coliform organisms have
been deleted, and the pH requirements for
ponds have been relaxed, the pond systems
must meet the 30 mg/1 (monthly average)
and 45 mg/1 (weekly average) values
for BOD5. In addition, they must meet
relaxed standards for suspended solids
except that relaxed standards for sus-
pended solids would not be authorized in
any case where such relaxation would
result in a water quality standards
violation in the receiving stream. In
such cases, regular secondary treatment
requirements would have to be met, or
treatment higher than secondary would
be required as necessary to meet the
water quality standards.
What are the relaxed standards or
effluent limitations that must be met?
The regulations say that the treatment
works must conform with the suspended
solids concentration achievable with best
waste stabilization pond technology.
Best waste stabilization pond technology
is, in turn, defined to mean "a suspended
solids value,'determined by the Regional
Administrator (or, if appropriate,
the State Director subject to EPA ap-
proval) , which is equal to the effluent
concentration achieved 90 percent of the
time within a State or appropriate
continguous geographical area by waste
stabilization ponds that are achieving
the levels of effluent quality estab-
lished for biochemical oxygen demand in
Section 133.102a» of the secondary
treatment regulations. In other words the
suspended solids value achieved 90
percent of the time is a statistical
number for suspended solids for pond
effluents that also meet the BODc
requirements. •>
These "90 percent of the time"
suspended solids values have been
16
-------
established in a number of states, and
they range from a low value of around
40 mg/1 to high values slightly greater
than 100 mg/1. In practice these
numbers will be used in NPDES permits as
30 consecutive day average values
or average values over the period of
discharge when the entire duration
of discharge is less than 30 days.
Within the next couple of months the
Environmental Protection Agency intends
to publish in the Federal Register a
listing of the values that are being
used in the various states as the sus-
pended solids concentration to be achiev-
ed 90 percent of the time. This notice
will also provide further explanation
of the program. The numbers that have
been developed to date are not con-
sidered permanent and will be re-evalu-
ated as additional data are available.
While it is not likely that any major
changes will be made, some minor changes
might be made in the future.
It is also probable that some states
will be re-evaluating their design
standards and design policies relative to
waste stabilization ponds. These
re-evaluations will be made with the idea
that certain upgrading may be desirable
in pond design to insure that newly
designed pond systems conform to the
ideas of best technology.
17
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EVALUATION OF FACULTATIVE WASTE STABILIZATION POND DESIGN
Brad A. Finney and E. Joe Middlebrooks*
INTRODUCTION
The principal objectives of this
paper are to outline the performance
of existing lagoon systems and to evalu-
ate several facultative waste stabili-
zation pond design equations. To satisfy
the need for reliable lagoon performance
data, in 197*1 the U.S. Environmental
Protection Agency sponsored four inten-
sive facultative lagoon performance
studies. These studies were located at
Peterborough, New Hampshire (EPA, 1977a),
Kilmichael, Mississippi (EPA, 1977c),
Eudora, Kansas (EPA, 1977d), and Corinne,
Utah (EPA 1977b). These studies encom-
passed 12 full months of data collection,
including four separate 30-consecutive-
day sample periods once each season.
A number of equations have been
proposed to design facultative waste-
water stabilization lagoons. Design
engineers must choose between these
often contradictory methods when design-
ing a facultative pond system that
will provide adequate wastewater treat-
ment at a reasonable cost. These
design techniques include simple design
criteria based on organic loading
and hydraulic detention time, empirical
design equations, and rational design
equations. Examples of each technique
will be used in conjunction with the data
collected at the four sites described
above.
SITE DESCRIPTION
Peterborough, New
Hampshire
The Peterborough facultative waste
stabilization lagoon system consists
of three cells operated in series with a
total surface area of 8.5 hectares
*Brad A. Finney is a Graduate
Assistant, and E. Joe Middlebrooks
is Dean, College of Engineering, Utah
State University, Logan, Utah.
(21 acres) followed by chlorination. A
schematic drawing of the facility is
shown in Figure 1. A chlorine residual
of 2.0 mg/1 is maintained at all times.
The facility was designed in 1968 on an
areal loading basis of 19.6 kg BOD5/day/
ha (17.5 Ibs BOD5/day/ac) with an ini-
tial average hydraulic flow of 1893
m3/day (0.5 mgd). At the design depth
of 1.2 m (4 ft), the theoretical hy-
draulic detention time would be 57 days.
The results of the study conducted during
1974-1975 indicated an actual average
areal loading of 15.6 kg BODg/day/ha
(13-9 Ibs BOD5/day/ac) and an average
hydraulic flow of 1011 m3/day (0.267
mgd). Thus, the actual theoretical
hydraulic detention time was 107 days.
Kilmichael, Mississippi
The Kilmichael facultative waste
stabilization lagoon system consists
of three cells operated in series with a
total surface area of 3-3 ha (8.1
acres). The effluent is not chlorinated.
A schematic drawing of the facili-
ty is shown in Figure 2.
The design load for the first cell
in the series was 67.2 kg BOD5/day/ha
(60 Ibs BOD5/day/ac). The second cell
was designed with a surface area equiva-
lent to 40 percent of the surface area of
the first cell. The third cell was
designed with a surface area equivalent
to 16 percent of the first cell. The
system was designed for a hydraulic flow
of 693 m3/day (0.183 mgd). The average
depth of the lagoons is approximately 2 m
(6.6 ft). This provides for a theoreti-
cal hydraulic detention time of 79 days.
The result of the study indicated that
the actual average organic load on the
first cell averaged 27.2 kg BOD5/day/ha
(24.3 Ibs BOD5/day/ac) and that the
average hydraulic inflow to the system
was 281 nP/day (0.074 mgd). Thus, the
actual theoretical hydraulic detention
time in the system was 214 days.
18
-------
Eudora, Kansas
The Eudora facultative waste stabi-
lization lagoon system consists of
three cells operated in series with a
total surface area of 7.8 ha (19.3
ac). A schematic diagram of the system is
shown in Figure 3. The effluent is
not chlorinated.
The facility was designed on an
areal loading basis of 38 kg BODc/day/ha
(34 Ibs BOD5/day/ac) with a hydraulic
flow of 1514 m3/day (0.4 mgd) . At the
designed operating depth of 1.5 m (5 ft),
the theoretical hydraulic detention time
would be 47 days. The results of the
study indicated that the actual average
organic load on the system was 19.0 kg
BOD5/day/ha (16.7 Ibs BOD5/day/ac)
and the actual average hydraulic flow to
the system was 506 m3/day (0.13 mgd).
Thus, the actual theoretical hydraulic
detention time in the system was 231
days.
Corlnne, Utah
The Corinne facultative waste
stabilization lagoon system consists of
seven cells operated in series with a
total surface area of 3.86 ha (9.53 ac).
A schematic drawing of the system is
shown in Figure 4. The effluent is
not chlorinated.
The facility was designed on an are-
al loading basis of 36.2 kg BODc/day/ha
(32.2 Ibs BOD5/day/ac) with a hydraulic
flow of 265 m3/day (0.07 mgd). With
a design depth of 1.2 m (4 ft), the
system has a theoretical hydraulic
detention time of 180 days. The results
of the study indicated that the actual
average organic load on the system was
14.1 kg BOD5/day/ha (12.6 Ibs BODs/day/
ac) and the actual average hydraulic flow
to the system was 694 m3/day (0.18 mgd).
Thus, the actual theoretical hydraulic
detention time in the system was 70
days.
TO CHLORINE CONTACT
TANK
Figure 1. Facultative lagoon system at Peterborough, New Hampshire (EPA, 1977a).
19
-------
A SAMPLING LOCATIONS
Figure 2. Facultative lagoon system at Kilmichael, Mississippi (EPA, 1977c)
EFFLUENT
Figure 3. Facultative lagoon system at
Eudora, Kansas (EPA, 1977d).
PERFORMANCE
Biochemical Oxygen Demand
(BOD5) Performance
The monthly average effluent bio-
chemical oxygen demand (8005) concen-
trations for the four previously de-
scribed facultative lagoon systems are
compared with the Federal Secondary
Treatment Standard of 30 mg/1 in Figure
5-
In general, all of the systems were
capable of providing a monthly average
effluent 8005 concentration of less than
30 mg/1 during the major portion of the
year. Monthly average effluent BODc
concentrations ranged from 1.4 mg/1
during September 1975 at the Corinne,
Utah, site, to 57 mg/1 during March 1975
20
-------
EFFLUENT
O SAMPLING
STATION
(ej ini
0.34 Hectares
(0.84 Acres )
©
3ZI
0,405 Hectares
(1.00 Acres)
0.405 Hectares
(1.00 Acres)
H
0.405 Hectares
(1.00 Acres)
ni
0.405 Hectares
(1.00 Acres)
0.405 Hectares
(1.00 Acres)
1.49 Hectares
(3,69 Acres)
Figure 4. Facultative lagoon system at Corinne, Utah (EPA, 1977b).
at the Peterborough, New Hampshire, site.
Monthly average effluent BODg con-
centrations tended to be higher during
the winter months (January, February,
March, and April) at all of the sites.
This was especially evident at the
Peterborough site where the ponds were
covered over by ice due to freezing
winter temperatures. The ice cover
caused the ponds to become anaerobic.
However, even when the ponds at the
Corinne site were covered over with ice
the monthly average effluent BOV<~, con-
centration did not exceed 30 mg/1.
None of the systems studied were
significantly affected by the fall
overturn. However, the spring overturn
did cause significant increases in
effluent BOD^ concentrations at two of
the sites. At the Corinne site two
different spring overturns occurred. The
first occurred in March 1975, with a peak
daily BODc concentration of 36 mg/1.
The second occurred during April 1975,
with a peak daily effluent BODc con-
centration of 39 mg/1. At the ludora
site, the peak daily effluent BOD5
concentration of 57 mg/1 occurred during
April 1975. The Kilmichael and Peter-
borough sites were not severely affected
by the spring overturn period.
The monthly average effluent BOD5
concentration of the Corinne lagoon
system never exceeded 30 mg/1 throughout
the entire study. The Eudora lagoon
system monthly average effluent BODg
concentration exceeded 30 mg/1 twice
during the entire study. The Kilmichael
lagoon system monthly average effluent
BOD5 concentration exceeded 30 mg/1 on
only two occasions during the study. The
Federal Secondary Treatment of 30 mg/1
was exceeded by the Peterborough lagoon
system monthly average effluent BOD5
concentration M of the 12 months studied.
The results of these studies in-
dicate that properly designed, maintain-
ed, and operated facultative waste
stabilization pond systems can produce
a high quality effluent. Although these
systems are subject to seasonal upsets,
they are capable of producing a low
biochemical oxygen demand (8005) ef-
21
-------
fluent which is suitable for polishing
by various processes. Since facul-
tative lagoon effluents exceed 30 mg/1
during a relatively small portion of
the year, it is possible to control the
discharge in such a manner as not
to exceed discharge standards.
Suspended Solids
Performance
The monthly average effluent sus-
pended solids concentrations for each
system are illustrated in Figure 6. At
the present there is no specific Federal
Secondary Treatment Standard effluent
suspended solids concentration for
facultative lagoons.
In general, the effluent suspended
solids concentrations of the facul-
tative lagoons follow a seasonal pattern.
Effluent suspended solids concentrations
are high during summer months when algal
growth is intensive and also during the
spring and fall overturn periods when
settled suspended solids are resuspended
from bottom sediments due to mixing. The
monthly average suspended solids con-
centrations ranged from 2.5 mg/1 during
September 1975 at the Corinne site to 179
mg/1 during April 1975, also at the
Corinne site. The high monthly average
effluent concentration of 179 mg/1 at the
Corinne site occurred during the spring
overturn period which caused a resuspen-
sion of settled solids.
The Eudora and Kilmichael sites
illustrate the increase in effluent
suspended solids concentrations due to
algal growth during the warm summer
months. However, the Peterborough and
Corinine sites were not significantly
affected by algal growth during the
summer months. In general, the Corinne
and Peterborough sites produced monthly
average effluent suspended solids
concentrations of less, than 20 mg/1.
During 10 of the 13 mo!hths studied,
the monthly average effluent suspended
solids concentration g,t the Corinne
site never exceeded 20, mg/1. However,
the monthly average effluent suspended
solids concentration at the Eudora site
was never less than 39 mg/1 throughout
the entire study.
O>
o
00
4O
3O
10
PETERBOROUGH, NH
(3 CELLS)
KILMICHAEL, MS
(3 CELLS)
EUDORA,KA
(3 CELLS)
o» CORINNE, UT
(7 CELLS)
FEDERAL DISCHARGE
\ STANDARD • 3Omg/I
\
i i I i 1 r 1 i I i i i i
SOND IFMAMJJASOND
1974 1975
MONTH
Figure 5. Monthly average effluent biochemical oxygen demand (BOD5).
22
-------
A 179
N,
O>
g
_1
o
100
90
80
70
60
50
40
o
UJ
Q
z
ID
Q.
W 30
V)
/ \
,
Q-"
EUDORA, KANSAS (3 Cells)
Q KILMICHAEL, MISSISSIPPI (3 Cells)
A CORINNE, UTAH (7 Cells)
O PETERBOROUGH, NEW HAMPSHIRE
(3 Cells)
"•a.
20 — /
^o--o- A.,..>4^
0
1 1 1 1 1
S 0 N D F
1974 1975
0-.-0 \
'"'••&•-
1 1 1 1 1
M A M J J
-W-°
1 1
A S
A
1 ^
"•LU
1 1 1
0 N D
1975
Figure 6. Monthly average effluent suspended solids for typical facultative lagoons.
The results of the studies indicate
that facultative lagoons can produce
an effluent which has a low suspended
solids concentration. However, ef-
fluent suspended solids concentrations
will be high at various times through-
out the year. In general, these sus-
pended solids are composed of algal
cells which may not be particularly
harmful to receiving streams. In areas
where effluent suspended solids standards
are stringent, some type of polishing
device will be necessary to reduce
facultative lagoon effluent suspended
solids concentrations to acceptable
levels.
Fecal Coliform
Removal
Performance
The monthly geometric mean effluent
coliform concentrations for the four
facultative lagoon systems are compared
with a concentration of 200 per 100 ml in
Figure 7.
Only the Peterborough, New Hamp-
shire, facultative lagoon system employs
chlorination. The other three facilities
do not practice disinfection. As illu-
strated in Figure 7, the chlorinated
Peterborough lagoon effluent never
exceeds a concentration of 10 fecal
coliform organisms per 100 ml. This
clearly indicates that facultative lagoon
effluent may be satisfactorily disin-
fected by the chlorination process.
For the three facultative lagoon
systems without disinfection processes,
the geometric mean monthly effluent fecal
coliform concentration ranged from 0.1
organisms/100 ml in June and September
1975, at the Corinne, Utah, lagoon system
to 13,527 organisms/100 ml in January
1975, at the Kilmichael, Mississippi,
lagoon system. In general, geometric
mean effluent fecal coliform concentra-
tions tend to be higher during these
periods. Periods of ice cover during
winter months would seriously affect
fecal coliform die-off due to sunlight
effects. The Eudora, Kansas, and the
Kilmichael, Mississippi, geometric mean
monthly effluent fecal coliform con-
centrations consistently exceeded 200
organisms/100 ml during winter operation.
The Corinne, Utah, lagoon system
never exceeded 200 organisms/100 ml
23
-------
E
O
UJ
o:
IO°
O
>
.£*
1^
A
S O N
D
1974
F
1975
M
i
A
I
M
i
S
N
D
1975
EUDORA,KANSAS (3 CELLS)
KILMICHAEL, MISSISSIPPI (3 CELLS)
CORINNE, UTAH (7 CELLS)
— PETERBOROUGH, NEW HAMPSHIRE (3 CELLS)
• PETERBOROUGH, NEW HAMPSHIRE (CHLORINATED)
Figure 7. Effluent monthly geometric average fecal coliform concentrations from
typical facultative lagoons.
even though this system did not practice
any form of disinfection. This system is
composed of seven cells in series.
Analysis of the fecal coliform concen-
trations between the seven cells in-
dicated that fecal coliforms were es-
sentially removed after the fourth cell
in the series (EPA, 1976b). The other two
facultative lagoon systems without
disinfection only utilize three cells in
series. However, fecal coliform die-off
is primarily a function of hydraulic
residence time rather than the absolute
number of cells in series.
The results of these studies in-
dicate that facultative lagoon effluent
can be chlorinated sufficiently to
produce fecal coliform concentration
less than 10 organisms per 100 ml. Two
of the systems studied could not produce
an effluent containing less than 200
fecal coliform/100 ml. This was probably
due to hydraulic short circuiting.
However, the Corinne, Utah, system study
clearly indicated that properly designed
facultative lagoon systems can signifi-
cantly reduce fecal coliform concentra-
tions.
EVALUATION OF DESIGN
METHODS
Design Criteria for Organic
Loading and Hydraulic
Detention Time
Canter and Englande (1970) reported
that most states have design criteria for
organic loading and/or hydraulic deten-
tion time for facultative waste stabili-
zation ponds. Design criteria are used
by the states to ensure that pond ef-
fluent water quality meets state and
federal discharge standards. Repeated
violations of effluent quality standards
by pond systems that meet state design
criteria indicate the inadequacy of the
24
-------
criteria. Reported organic loading
design criteria averaged 21.2 kg BODc/
ha/day (26.0 Ib BODs/ac/day) in the
north region (above 42° latitude), 49.4
kg BOD5/ha/day (44 Ib BOD5/ac/day)
in the southern region (below 37° lati-
tude) and 37.0 kg BOD5/ha/day (33 Ib
BOD5/ac/day) in the central region.
Reported design criteria for detention
time averaged 117 days in the north, 82
days in the central, and 31 days in the
south region.
Design criteria for organic loading
in New Hampshire is 39-3 kg BOD5/ha/day
(35 Ib BOD5/ac/day). The Peterborough
treatment system was designed for a load-
ing of 19.6 kg BOD5/ha/day (17.5 Ib
BOD5/ac/day) in 1968 to be increased as
population increased to 39.3 kg BOD5/ha/
day (35 Ib B005/ac/day) in the year
2000. Actual loading during 1974-1975
averaged 16.2 kg BOD5/ha/day (14.4 Ib
BOD5/ac/day) with the highest loading
being 21.2 kg BOD5/ha/day (18.9 Ib
BODc/ac/day). Although the organic
loading was substantially below the state
design limit, the effluent exceeded the
federal standard of 30 mg BODg/l during
the months of October 1974, February,
March, and April 1975.
Mississippi's design criteria for
organic loading is 56.2 kg BODc/ha/day
(50 Ib BOD5/ac/day). The Kilmichael
treatment system was designed for a
loading of 43 kg BOD5/ha/day (38 Ib
BODc/ac/day). Actual loading during
1974-1975 averaged 17.5 kg BOD5/ha/day
(15.6 Ib BODc/ac/day) with a maximum of
24.7 kg BOD5/ha/day (22 Ib BOD5/ac/day)
and yet the federal BODc effluent stan-
dard was exceeded twice during the sample
year (November and July).
The design load for the Eudora,
Kansas, system was the same as the state
design limit, 38.1 kg BOD5/ha/day (34
Ib BODc/ac/day). Actual loading during
1974-1975 averaged only 18.8 kg BOD5/ha/
day (16.7 Ib BOD5/ac/day) with maximum
of 31.5 kg BOD5/ha/day (28 Ib BOD5/ac/
day). The federal BOD5 effluent stan-
dard was exceeded 3 months during the
sample year (March, April, and August).
Utah has both an organic loading
design limit, 45 kg BOD5/ha/day (40
Ib BOD5/ac/day) on the primary cell and
a winter detention time design criteria
of 180 days. Design loading for the
Corinne system was 36.2 kg BOD5/ha/day
(32.2 Ib BOD5/ac/day) and design de-
tention time was 180 days. Although
the organic loading averaged 33-6 kg
BOD5/ha/day (29.8 Ib BOD5/ac/day) on
the primary cell, during two months of
the sample year it exceeded 56.2 kg
BOD5/ha/day (50 Ib BOD5/ac/day). Aver-
age organic loading on the total system
was 13.0 kg BOD5/ha/day (14.6 Ib BOD5/
ac/day), and the hydraulic detention
time was estimated to be 88 days during
the winter. Regardless of the deviations
from the state design criteria, the
monthly BODg average never exceeded
the federal effluent standard.
A summary of the state design
criteria for each location and actual
design values for organic loading and
hydraulic detention time are shown in
Table 1. Also included is a list of the
months the federal effluent standard
for BOD5 was exceeded. Note that the
actual organic loading for all four
systems are nearly equal, yet as the
monthly effluent 8005 averages shown in
Figure 5 indicate, the Corinne system
consistently produces a higher quality
effluent. This may be a function of the
larger number of cells in the Corinne
system; seven as compared to three for
the rest of the systems. Hydraulic short
circuiting may be occurring in the three
cell systems resulting in a shorter
actual detention time than exists in the
Corinne system. Detention time may also
be affected by the location of pond cell
inlet and outlet structures. As shown in
Figure 4, the outlet structures are at
the furthest point possible from the
inlet structures in the Corinne, Utah,
system. At the Eudora, Kansas, system
shown in Figure 3, large "dead zones"
undoubtedly occur in each cell due to the
unnecessarily short distance between
inlet and outlet structures. These dead
zones result in decreased hydraulic
detention and increased effective organic
loading rate. The extremely poor per-
formance of the Peterborough system
during the winter months suggests a need
for New Hampshire to evaluate their
organic loading standards.
Empirical Design
Equations
In a survey of primary facultative
ponds in tropical and temperate zones,
McGarry and Pescod (1970) found that
areal BODg removal (Lp, Ib/ac/day)
may be estimated through knowledge of
areal 6005 loading (Lo, Ib/ac/day)
using Equation 1.
= 9.23 + 0-725 Lo
- (1)
It was reported that the regression
equation had a correlation coefficient
of 0.995 and a 95 percent confidence
interval of +_ 29.3 Ib BOD5/ac/day re-
moval. The equation was reported to be
valid for any loading between 30 and 500
Ib BOD5/ac/day. McGarry and Pescod
also found that under normal operating
25
-------
ranges, hydraulic detention time and pond
depth have little influence on percentage
or areal BOD5 removal.
Equation 1 was applied to the
primary cell of the Peterborough, Eudora,
and Corinne facultative pond systems.
The Kilmichael system could not be used
because the primary cell loading was
below 30 Ib/ac/day. The equation pre-
dicted higher removal (Lr) than was
observed for all three systems although
the observed data fell within the 95
percent confidence interval. The. results
obtained from Equation 1 are summarized
in Table 2 and a plot of the equation and
observed data is shown in Figure 8. As
can be seen from Figure 8, the relative
magnitude of the 95 percent confidence
interval at loadings commonly found in
the United States (under 100 lb/BOD5/
ac/day) makes the equation practically
useless as a tool for facultative waste-
water stabilization pond design. For
example, at a loading of 80 Ib BOD5/
ac/day, Equation 1 predicts, at a 95
percent confidence level, a range of
removals from 37.9 to 96.5 Ib BODs/
ac/day.
Larsen (1974) proposed an empirical
design equation, developed by using data
from a one-year study at the Inhalation
Toxicology Research Institute, Kirtland
Air Force Base, New Mexico. The In-
stitute's facultative pond system con-
sists of one 0.66 ha (1.62 ac) cell
receiving waste from 151 staff members,
1300 beagle dogs, and several thousand
sm,all animals.
Larsen found that pond surface area
could be estimated by use of the follow-
ing equation.
MOT = (2.468RED+2.468TTC+23.9/TEMPR
+150.0/DRY)*106 (2)
Table 1. Summary of state design standards, design and actual values for organic
loading and hydraulic detention time.
Organic Loading Theoretical Hydraulic
(kg BOD5/ha/day) Detention Time (Days) Months Effluent
State Exceeded 30 mg/1 BODj
Design Actual State Standard
Location Standard Design (1974-1975) Design Design Actual
Peterborough, NH 39.3 19.6
Kilmichael, MS 56.2 43.0
Eudora, KS 38.1 38.1
Corinne, UT 45.0* 36.2*
16.2 None 57
17.5 None 79
18 .8 None 47
29.7* 180 180
14.6**
107 Oct., Feb., Mar., Apr.
214 Nov., July
231 Mar. , Apr. , Aug.
70 None
88***
*Primary Cell
**Entire System
***Estimated From Dye Study
Table 2. Actual and predicted areal BOD removal from primary facultative pond cells.
Primary Cell Primary Cell
Average Annual Areal Average Annual Areal McGarry and Pescod Equation
BOD Loading (Lo) BOD Removal Areal BOD Removal (Lr) 95% Confidence Interval
Location (Ib/ac day) (Ib/ac day) (Ib/ac day) (Ib/ac day)
Peterborough, NH 36.5
Eudora, KS 42.0
Corinne, UT 32.9
24.2
35.0
19.2
35.7
39.7
33.1
6.39 £ Lr < 65.0
10.4 <. Lr _< 69.0
3.78 <_ Lr <, 62.4
26
-------
where the dimensionless products
,,_„, surface area (solar radiation)
MOT = *
1/3
RED
TTC
influent flow rate (influent BODr)
influent BODr - effluent BODg
influent BOD
wind speed (influent BODc)
(solar radiation) '
1/3
TEMPR = ^-agoon liquid temperature
air temperature
DRY = relative humidity
Table 3 lists the units for the
parameters needed in Equation 2.
Table 4 lists the dimensionless products,
and the unit conversion factors required
to make them dimensionless when cal-
culated in the units indicated in Table
3. According to Larsen, since the design
IOO
9O
95%
CONFIDENCE
INTERVAL
PETERBOROUGH, NH
4O 5O 6O 7O SO 9O IOO
AREAL BOD LOADING (Lo),lb/AC DAY
Figure 8. McGarry and Pescod equation for areal 6005 removal as a function of BODc
loading.
27
-------
Table 3. Larsen equation input parameter
units.
Parameter
Wind Speed
Solar Radiation
Relative Humidity
Air Temperature
Lagoon Temperature
Influent Flow Rate
Influent BOD
Effluent BOD
Pond Area
Units
Miles /Hour
BTU/Ft2 Day
%
OF
OF
gal/day
mg/1
mg/1
Ft2
is in dimensionless form, it may be
correctly applied to any geographical
To calculate pond area required for
a specific BOD5 removal, Larsen sug-
gests using the least favorable climatic
conditions. Pond depth must be from 3 to
5 feet.
To ensure that a maximum pond
surface area was obtained when applying
the Larsen equation to the four faculta-
tive waste stabilization pond systems,
the following rules were observed.
1. Use winter (average of December
and January) solar radiation data.
With the exception of the Corinne system,
solar radiation data were obtained
from Visher (1966). The solar radiation
data for the Corinne system were obtained
from EPA (1977b).
2. Use lowest monthly relative
humidity and yearly average windspeed.
These data were obtained from the nearest
reporting weather station listed by NOAA
(1974).
3. Use winter (average of December
and January) BODg influent and effluent
concentration, hydraulic loading, pond
temperature, and daily average air
temperature.
To determine the effect of using the
Larsen equation on multicell facultative
ponds, it was applied to both the entire
system and the primary cell for each lo-
cation. The data used in Larsen1s equa-
tion verification are shown in Table 5.
Table 4. Dimensionless products and unit
conversion factors.
Dimensionless Product Unit Coversion Factor
MDT
RED
TTC
TEMPR
DRY
1.0783 x 107
1
0.0879
1.0
1.0
The actual and predicted pond
surface areas from the Larsen equation
are shown in Table 6. In each case the
Larsen equation underestimated the
pond surface area required for a par-
ticular BODc removal. The equation
proved totally useless in designing
multiple cell lagoons with prediction
errors ranging from 190 to 248 percent.
Prediction errors for the single cell
surface areas range from 18 to 98 per-
cent".
Predicted pond area was found to be
insensitive to the 8005 removal frac-
tion (the dimensionless product RED).
For example, the Corinne, Utah, site
predicted pond area was 1.12 ha for 100-
percent 8005 removal (RED=1) while the
predicted area was 1.06 ha for zero
percent BODg removal (RED=0). Predicted
pond area was also found to be insensi-
tive to the dimensionless product TTC.
Therefore, letting
2.468
RED
2.468
TTC
= constant = C
The Larsen equation reduces to
MOT = (C + 23.9/TEMPR + 150/day)*10C
(3)
Substituting for the dimensionless
products and solving for surface area
(A) yields:
A = f fc + 23 9 ( air, temP-'\
IL \j>ond temp.J
, _ 150 _ *-m6'
']~\
I J
_ _
relative humidity
(influent flow rate)(inf luent BOD,-)
(solar radiation)
T7T
28
-------
Table 5. Input data used for Larsen equation.
Pond Air Influent System Primary Cell
Wind Solar Relative Tempera- Tempera- flow Influent Effluent Effluent
Location
Peterborough, NH
Kilmichael, MS
Eudora, KS
Corinne, UT
Speed Radiation Humidity
(MPH) (BTU/Ft2 Day) (%)
5.8
7.6
10.9
2.0
460
735
827
606
48
47
46
23
ture
(oF)
37.8
48.2
46.2
35.0
ture
(0F)
23.8
44.6
44.3
27.7
Rate BOD5
(gal/day) (mg/1)
2.36x105
7.43x104*
1.17x105
7.66x104
133.
139.
363.
120.
BOD5
(mg/1)
11.6
23.1
17.1
7.2
BOD5
(mg/1)
45.0
22.5
45.2
21.0
Table 6. Predicted and actual pond surface area.
Location
(ha) * 0.405 - ac
Actual Surface Area
Primary Total
(ha) (ha)
Predicted Surface Area
Primary Total
(ha) (ha)
Prediction Error
For Primary For Total
Peterborough, NH
Kilmichael, MS
Eudora, KS
Corinne, DT
3.40
2.10
3.16
1.49
8.50
3.21
7.82
3.86
2.87
1.06
2.32
1.10
2.93
1.06
2.33
1.11
18
98
36
34
190
203
236
248
Surface area is no longer a function of
pond performance but of organic loading,
hydraulic loading and climatic condition;
therefore, the Larsen equation has less
merit than state design criteria based on
organic loading and hydraulic detention
time.
Another empirical equation for the
design of facultative waste stabi-
lization ponds was proposed by Gloyna
(1976). The equation, useful in deter-
mining pond surface area, is as follows:
V =3.5xlO-5QLa [e(35-T)] ff . .(4)
where
V = pond volume (m3)
Q = influent flow rate (I/day)
La = ultimate influent BODU or
COD (mg/1)
6 = temperature coefficient
T = pond temperature (°C)
f = algal toxicity factor
f = sulfide oxygen demand
The BODc removal efficiency can be
expected to be 80 to 90 percent based on
unfiltered influent samples and filtered
effluent samples. A pond depth of 1.5 m
is suggested for systems with significant
seasonal variations in temperature and
major fluctuations in daily flow. Sur-
face area design using the Gloyna
equation should always be based on a 1 m
depth. According to Gloyna, the algal
toxicity factor (f) can be assumed to be
equal to 1.0 for domestic wastes and many
industrial wastes. The sulfide oxygen
demand (f ) is also equal to 1.0 for
SOij equivalent ion concentration of
less than 500 mg/1. Gloyna also suggests
the use of the average temperature of the
pond in the critical or coldest month.
Sunlight is not considered to be critical
in pond design but may be incorporated
into the Gloyna equation by multiplying
29
-------
the pond volume by the ratio of sunlight
in the particular area to the average
found in the southwest U.S.
The data used to evaluate the Gloyna
equation is shown in Table 7. Since
ultimate BOD data were not available, COD
data were used. To smooth out wild
fluctuations in influent flow rate and
influent COD, averages from the 3 months
with the lowest pond temperatures were
used. The coldest monthly average cell
temperature was used for the pond temper-
ature. Both the algal toxicity factor
and sulfide oxygen demand factor were
assumed equal to 1.0. The solar radiation
data are the January monthly average as
reported by Visher (1966). The solar
radiation in the southwest United States
was assumed to be 300 cal/cm^ day (Visher,
1966). The depth of the Peterborough
and Corinne systems at 1.2 m is less than
recommended by Gloyna. The depth of
the Kilmichael and Eudora systems are 2 m
and 1.5 m respectively.
The actual pond area, BODg removal
efficiency, and suggested pond area as
determined by the Gloyna equation without
the sunlight correction are presented in
Table 8. The areas determined by the
equation are substantially larger than
the actual area for most ponds in the
Kilmichael, Eudora, and Corinne systems
yet the actual 8005 removal falls
within the range expected (80 to 90
percent). Pond areas determined by the
Gloyna equation are somewhat smaller than
the actual areas for the Peterborough
system, yet 6005 removal is consider-
ably less than expected. Since the
solar radiation at all the sites is less
than the solar radiation in the south-
west U.S., use of the sunlight correction
would only improve the equation predic-
tions for the Peterborough system. The
i-nconsistent results obtained from the
'Gloyna equation point out its weakness as
a design tool.
Rational Design
Equations
Marais (1970) proposed three kinetic
models of increasing complexity de-
scribing facultative waste stabilization
pond performance. Only the first
two models will be discussed here.
Model 1 assumes:
instantaneous mixing
the pond contents,
equals pond BOD5;
1) Complete and
of influent with
hence effluent BODg
2) Degradation is
Table 7. Influent flow rate, influent
data used in Gloyna equation.
COD, pond temperature and solar radiation
Location
Influent Flow
Rate, Q
(I/Day)
Influent
COD, La
(mg/1)
Pond
Temperature, T
Solar
Radiation
(cal/en>2/day)
Peterborough, NH
Pond 1
Pond 2
Pond 3
Kilmichael, MS
Pond 1
Pond 2
Pond 3
Eudora, KS
Pond 1
Pond 2
Pond 3
Corinne, HT
2.69 x 105
2.81 x 105*
5.25 x 1(P
4.87 x 105
222
154
136
256
124
117
606
172
133
2.7
2.0
2.0
8.9
8.4
8.0
2.9
3.2
3.1
125
225
250
180
Pond 1
Pond 2
Pond 3
Pond 4
Pond 5
Pond 6
Pond 7
168
110
98
105
100
87
79
1.2
0.8
0.8
0.9
0.8
1.1
1.4
(I/day) * 0.264 = gal/day
*Monthly data not available, annual average
30
-------
Table 8. Comparison of actual pond area and BODs removal efficiencies compared to
areas determined by Gloyna equation without sunlight correction.
Location
Peterborough, DM
Pond 1
Pond 2
Pond 3
Kilmichael, MS
Pond 1
Pond 2
Pond 3
Eudora, KS
Pond 1
Pond 2
Pond 3
Corinne, UT
Pond 1
Pond 2
Pond 3
Pond 4
Pond 5
Pond 6
Pond 7
Actual Pond
Area
(ha)
3.4
2.3
2.6
2.1
0.85
0.34
3.2
1.5
3.2
1.5
0.41
0.41
0.41
0.41
0.41
0.34
BOD5 Removal
Efficiency*
(%)
61
40
37
98
89
85
95
82
87
95
85
82
84
83
84
73
Pond Area Determined
by Gloyna Equation
(ha)
2.9
2.1
1.9
2.1
1.1
1.0
15.3
4.2
3.3
4.5
3.1
2.7
2.9
2.8
2.4
2.1
(ha) * 0.405 - ac
*Based on unfiltered influent and filtered effluent
according to first order reaction with
the degradation constant independent
of temperature and retention time; 3) No
pollution losses due to seepage; 4)
No settlement of influent 8005 as
sludge. Under equilibrium conditions
and neglecting seepage and evaporation
losses, pond effluent quality can be
predicted by the following equation:
modified as follows: 2) Degradation rate
is a first order reaction with the
reaction rate dependent on temperature
according to the Arrhenius equation
KT
(T-T0)
(6)
KR + 1
in which
P =
(5)
pond or effluent 801)5 or
organism concentration
Pi = influent BOD5 or
organism concentration
K = first order degradation
constant (I/day)
R = detention time (days)
According to Marais, Equation 5 has
been successfully used in Southern
Africa to predict the reduction of fecal
bacteria using a value of K equal
to 2.0/day.
Model 2 is identical to Model 1,
except for assumption 2), which is
in which
KT
degradation constant
at temperature T
degradation constant
at temperature T0
9 = temperature coefficient
The equation for Model 2 then becomes
P..
P =
R + 1
(7)
An attempt was made to verify Model
1 and Model 2 using fecal coliform
data from the primary cell of the Eudora,
Kansas, and Corinne, Utah, treatment
ponds. Instead of predicting effluent
31
-------
quality, the degradation constant, K, was
determined by using the following equa-
tion
K =
in which
(8)
PI = influent fecal coliform
concentration (colonies/100 ml)
P = effluent fecal coliform con-
centration (colonies/100 ml)
R = detention time (days)
A constant value of K would verify Model
1. To verify Model 2, Kj was deter-
mined using the following equation
KT
>(T-20)
(9)
in which
6 = 1.047 (Bishop and Grenney,
1976) j , .
KT = value of K found in Model I
(I/day)
A .constant value of KTo would verify
Model 2.
The monthly average detention time
and fecal coliform influent and effluent
concentrations used as input data for
both models are shown for the Eudora and
Corinne systems in Tables 9 and 10,
respectively. Computed values of K for
the Eudora system ranged from 0.31 to
2.98 with a mean of 0.91. Computed values
of KT had a mean of 1.15 and ranged
from 0°.44 to 2.64. Computed values of K
for the Corinne system averaged 3-2 and
ranged from 0.81 to 6.9- Computed values
for KX had a mean of 4.9 and ranged
from 0.^0 to 10.0. The computed values
Table 9. Primary cell monthly average detention time and influent and effluent fecal
coliform for Eudora, Kansas.
Month
Sept.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May
June
July
Aug.
Dentention Time
(Days )
88.9
93.1
94.4
107.4
109.2
70.1
74.6
85.3
101.2
107.2
123.9
116.0
Influent
Fecal Coliform
(colonies /100 ml)
3.7 x 106
1.9 x 106
7.3 x 105
1.8 x 106
1.3 x 106
1.3 x 106
9.2 x 105
1.7 x 106
2.0 x 106
3.5 x 106
6.3 x 10&
3.3 x 106
Effluent
Fecal Coliform
(colonies /100 ml)
6.2 x 104
5.3 x 104
2.4 x 104
1.3 x 104
3.0 x 104
3.4 x 104
1.6 x 104
3.9 x 104
3.8 x 104
1.3 x 104
1.7 x 104
2.8 x 104
Table 10. Primary cell monthly average detention time and fecal coliform influent
and effluent concentrations for the Corinne, Utah, pond.
Month
Jan.
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Dentention Time
(Days)
44.5
22.7
19.6
23.2
28.5
27.3
20.7
19.0
21.1
17.7
37.2
71.7
Influent
Fecal Coliform
(colonies /100 ml)
5.2 x 105
3.0 x 105
1.0 x 105
3.4 x 105
5.7 x 105
3.8 x 105
3.4 x 105
4.7 x 105
8.3 x 105
9.6 x 105
1.1 x 106
8.3 x 105
Effluent
Fecal Coliform
(colonies /100 ml)
1.4 x 104
1.1 x 104
1.0 x 104
4.0 x 103
2.9 x 103
2.0 x 103
3.9 x 103
6.2 x 103
1.6 x 104
1.9 x 104
8.4 x 103
7.8 x 103
32
-------
of K and KT for the Eudora and Corrine
systems are shown in Figures 9 and 10
respectively. The wide variation in
both K and KT reveal the limitations
of using either Model 1 or Model 2 in the
design of a facultative waste stabiliza-
tion pond.
In contrast to the hydraulic flow
assumption made by Marais, Thirumurthi
(197^) states that a completely mixed
flow formula should never be used for
the rational design of stabilization
ponds. Thirumurthi found that faculta-
tive ponds exhibit nonideal flow patterns
and recommended the use of the following
chemical reactor equation for pond
design:
4ae
%d
C7
(l+a)2ea/2d-(l-a)2e-1'2d
. (10)
in which
c« =
effluent 8005 (mg/1)
influent 8005 (mg/1)
first order BODc removal
coefficient (I/day)
/ 1 +Ktd
mean detention time (days)
dimensionless dispersion number
Thirumurthi defined K in terms of a
standard BOD5 removal coefficient Ks
using the following equation
(11)
in which
CTe
= correction factor for
temperature
= correction factor for
organic load
w
h-
i*
W
O
O
z
O
I
<
S
liJ
O
~r
N
-1
D
1974
F M A M
"T
J
~r
A
1975
Figure 9. Computed values of K and
MONTH
for Eudora, Kansas.
33
-------
IO
I.
I-
o
o
z 4
g
i-
a:
o
FMAMJJASOND
1975
MONTH
1976
Figure 10. Calculated values of K and Ks for Corinne, Utah.
= correction factor for
toxic chemicals
A very narrow range of values, 0.042 to
0.071, was found for Ks. The average
value of Ks was found to be 0.056/day.
Values of Ks were calculated for
each cell of the Corinne, Utah, faculta-
tive stabilization pond. A narrow range
of values for Ks would verify Equa-
tion 10. Using the method described by
Levenspiel (1972), data from dye studies
reported in EPA (1977b) were used to
calculate the cell mean hydraulic deten-
tion time and dispersion coefficient.
Cje and Co were calculated using the
following equations.
"Te
(12)
where
e = 1.036
T = pond temperature (°C)
and
(13)
where
L = organic load (kg/ha/day)
The correction for toxic chemicals was
assumed to be unity.
The data used to calculate Ks for
each cell are shown in Table 11. Cal-
culated values of Ks, shown in Table
12, had a mean of 0.066/day and ranged
from -0.004 to 0.127. The wide range
of values found for Ks indicated the
need for further refinement in the
correction factors used to calculate K.
Thirumurthi's assumption of nonideal flow
does seem to be supported by the values
found for d, the dispersion coefficient.
The largest value of d was 1.71, with a d
of approximately 5.0 required before
Marais1 completely mixed flow assumption
becomes valid.
CONCLUSIONS
None of the three types of models
for facultative waste stabilization
pond design discussed in this paper were
found to be adequate. Federal dis-
charge standards were often violated when
a pond design satisfied state organic
34
-------
Table 11. Summary of data used to calculate K~ for each cell of the Corinne, Utah,
facultative waste stabilization pond.
Pond
Number
1
2
3
4
5
6
7
Month
Jan.
May
June— July
May
June-July
May
June-July
Influent
BOD5, Cl
(mg/1)
121.5
32.8
16.6
33.4
6.7
35.6
7.4
Effluent
BOD5, Cl
(fflg/1)
38.1
28.1
10.5
35.0
4.5
32.3
3.7
Organic
Loading, L
kg BOD5/ha/day)
33.4
51.7
11.1
64.5
12.5
56.0
16.5
Mean Hydraulic
Detention Time,
t (days)
41.3
11.7
9.6
12.3
12.0
12.7
13.6
Dispersion
Coefficient, d
0.395
1.18
1.71
1.12
0.733
0.877
0.435
Pond
Temperature, T
(°C)
1.9
17.8
18.2
8.0
23.0
11.8
23.0
(kg/ha/day) * 0.893 = Ib/ac/day
Table 12. Calculated values of the stan-
dard BOD removal coefficient,
K^, for tiie Corinne, Utah, pond.
Cell
1
2
3
4
5
6
7
Calculated Ks
0.096
0.025
0.127
-0.004
0.094
0.017
0.105
loading and hydraulic detention time
design criteria. The three empirical
design equations and the two kinetic
design models yielded predictions not
substantiated by published pond perfor-
mance data. The two kinetic models
differed in the basic assumptions about
the hydraulic flow pattern, but neither
model described the measured performance.
The hydraulic detention time is used
in many of the design methods and yet
very little research has been done in
determining factors influencing actual
hydraulic residence time. Consistent
prediction of pond performance by any
design method without accurate projec-
tions of hydraulic residence time is
impossible. It is recommended that
future research on pond performance
consider the effect of physical and
climatic conditions on hydraulic re-
sidence time. Once residence time can be
accurately predicted, perhaps present
design methods can be modified to satis-
factorily predict pond performance.
REFERENCES
Bishop, A. B., and W- J. Grenney. 1976.
Coupled Optimization-Simulation
Water Quality Model. Journal of the
Environmental Engineering Division,
ASCE, 12(EE5):1071-1086.
Canter, L. W., and A. J. Englande. 1970.
States' Design Criteria for Waste
Stabilization Ponds. Journal WPCF
42(10) i
EPA
Environmental Protection Agency.
1977a. Performance Evaluation
of Existing Lagoons-Peterborough,
New Hampshire. EPA-600/2-77-085 .
Environmental Protection Technology
Series. Municipal Environmental
Research Laboratory, Cincinnati,
Ohio.
EPA, Environmental Protection Agency.
1977b. Performance Evaluation
of an Existing Seven Cell Lagoon
System. EPA-600/2-77-086 . Environ-
mental Protection Technology Series.
Municipal Environmental Research
Laboratory, Cincinnati, Ohio.
EPA, Environmental Protection Agency.
1977c. Performance Evaluation
of Kilmichael Lagoon. EPA-600/2-77-
109. Environmental Protection
Technology Series. Municipal
Environmental Research Laboratory,
Cincinnati, Ohio.
EPA, Environmental Protection Agency.
1977d. Performance Evaluation
of an Existing Lagoon System at
Eudora, Kansas. EPA-600/2-77-1 67 .
Environmental Protection Technology
Series. Municipal Environmental
35
-------
Research Laboratory, Cincinnati,
Ohio.
Gloyna, Ernest F. 1976. Facultative
Waste Stabilization Pond Design.
In Ponds as a Wastewater Treatment
Alternative. Water Resources
Symposium No. 9, edited by E. F.
Gloyna, J. F. Malina, Jr., and E. M.
Davis. Center for Research in Water
Resources, University of Texas,
Austin, Texas. p. 143-157.
Larsen, T. B. 1974. A Dimensionless
Design Equation for Sewage Lagoons.
Dissertation, University of New
Mexico, Albuquerque, New Mexico.
Levenspiel, Octave. 1972. Chemical
Reaction Engineering. Second
Edition. John Wiley and Sons, Inc.,
New York, N.Y. 578 p.
Marais, G.v.R. 1970. Dynamic Behavior
of Oxidation Ponds. 2nd Inter-,
national Symposium for Waste Treat-
ment Lagoons. Missouri Basin Eng.
Health Council. Kansas City,
Missouri, p. 15-46.
McGarry, M. C., and M. B. Pescod. 1970.
Stabilization Pond Design Criteria
for Tropical Asia. 2nd Internation-
al Symposium for Waste Treatment
Lagoons, Missouri Basin Eng. Health
Council, Kansas City, Missouri.
p. 114-132.
NOAA, National Oceanic and Atmospheric
Administration. 1974. Climates
of the States. Water Information
Center, Inc., Port Washington, N.Y.
2 Vols. 975 p.
Thirumurthi, Dhandapani. 1974. Design
Criteria for Waste Stabilization
Ponds. Journal WPCF, 46(9):2094-
2106.
Visher, S. S. 1966. Climatic Atlas of
the United States. Harvard Univer-
sity Press, Cambridge, Mass. 402 p.
36
-------
WASTE STABILIZATION POND SYSTEMS
Earnest F. Gloyna
and
Lial F. Tischler*
INTRODUCTION
Waste stabilization pond systems
(WSPS) providing Bppropriate and e~COTronii-
cal remedies have been discussed by many
engineers (Gloyna, Malina, Davis, 1976).
It has been demonstrated that properly
designed and operated waste stabilization
pond systems are highly effective for
treating wastewaters generated by the
production of basic organic chemicals and
related products such as synthetic
polymers and resins (Engineering-Science,
1977).
TERMINOLOGY
Terminology used herein is as
follows:
(1)
Anaerobic Waste Stabilization
Pond (AWSP) is an unmixed basin designed
to remove organic materials by anaerobic
biological activity.
(2) Mechanically Aerated Pond (MAP)
is a basin which is mechanically mixed
and aerated to allow removal of organic
materials by predominantly aerobic and
facultative microorganisms. Sufficient
mixing and aeration is applied to main-
tain aerobic conditions throughout the
water column and may suspend up to 200
mg/1 of biotnass. Anaerobic conditions
may prevail in the solids which settle.
(3) Facultative Waste Stabilization
Pond (FWSP) is a basin that provides an
aquatic environment in which dissolved
oxygen is available in the upper strata,
a facultative zone exists throughout most
of the depth and an anaerobic layer is
present near the bottom. Aeration is
•Earnest F. Gloyna is Dean and Joe
J. King Professor, College of Engineer-
ing, The University of Texas at Austin;
and Lial F. Tischler is Vice President,
Engineering Science, Incorporated,
Austin, Texas.
provided by algal photosynthesis and
natural reaeration across the air-water
interface.
( 4 ) f.£ii^hiHS_iie.I°^i£l_Wa.^t e
Stabilization Pond (PWSP) is an unmixed,
relatively shallow basin which is lightly
loaded with organic material and is
designed to remove organics in the
wastewater. Most of the water column
predominantly contains dissolved oxygen,
although again, the bottom sediments
may be anaerobic. This type of pond is
frequently used as a polishing pond. The
effluent of a multiple pond system is
more uniform, and the bacterial count
associated with human wastes is greatly
reduced.
( 5 ) Wjj^ !,£_ J3 t;_aj) j. J. ±zat± o _n_..
Sy.£t;e_mE! (WSPS) are combinations of
the above processes designed for bio-
logical treatment of wastewaters con-
taining organic materials, Figure 1.
POND ECOLOGY
The major biological reactions which
occur in waste stabilization ponds
include: (a) oxidation of carbonaceous
organics by aerobic bacteria, (b) nitri-
fication of nitrogenous material by
bacteria, (c) reduction of carbonaceous
organics by anaerobic bacteria living in
benthal deposits and bottom liquids, and
(d) oxygenation of surface liquids by
algae. For biodegradable wastewaters,
the weight of cells produced is roughly
equal to 0.5 and 0.6 times, respectively,
the weight of chemical oxygen demand
(COD) and biochemical oxygen demand, 5
days at 20°C (6005) removed.
Methane fermentation is an essential
reaction in anaerobic ponds. One of the
controlling factors in an anaerobic
lagoon system is the narrow pH range (6.8
to 7.2) permissible under methane fer-
mentation. This limitation is very
important since acid production must be
followed immediately by methane fermenta-
tion .
37
-------
!
I
I
-T--FWSP-PWSP
RECIRC. OPTIONAL—1
UNIFORM OR
REGULATED
RELEASE
Figure 1. Possible treatment trains as-
sociated with facultative
waste stabilization ponds.
A facultative pond can provide an
anaerobic environment near the bottom, a
buffer zone throughout the middle, and an
aerobic zone near the top. The designer
must remember to provide enough surface
area or photosynthetic oxygen to take
care of the initial soluble BOD plus that
released by anaerobic decomposition and
to compensate for any chemical oxygen
demand.
There must be sufficient surface
area and light available to accommodate
the required production of photosynthetic
oxygen. Similarly, the detention
requirements must accommodate the rate of
oxygen utilization. Significant vari-
ables and controlling parameters include
illumination, nutrient, and temperature.
Radiation energy required for the
production of each gram (gm) of oxygen
has been determined to be about 15 x
103 kilograys (3,580 cal) (Oswald,
1963). One gm of cell material is
theoretically equivalent to about 1.6 gms
of oxygen. Assuming that algal cell
substances contain 85 percent organic
matter, the oxygen yield per gm of
ash-included organic matter is about 1.35
gm. Oxygen production values ranging
from 2.6 mg 02/hr to 13-0 rag 02/hr
under ideal conditions have been re-
ported (Ichimura, 1968). This level of
oxygen production represents 2.6 to
12.9 gms of dissolved oxygen/m3 per
hour (7 to 35 pounds per acre foot
per hour.
The overall performance of a pond
system is highly temperature dependent.
Sludge deposits will be degraded by
anaerobic bacteria and throughout most
of the pond depth the soluble BOD will be
biodegraded by facultative bacteria.
Thermal stratification of the pond liquid
is occasionally responsible for main-
taining separate aerobic and anaerobic
zones for extended periods of time.
Thus, designs reflect the relatively
slower biodegradation rates of anaerobic-
facultative systems in contrast to the
more rapid rates exhibited by truly
aerobic-facultative systems. The useful
range of a facultative pond is 5°C to
about 35°C, the lower limit being due
to retardation of aerobic bacteria and
algal activity. Anaerobic bacteria are
not very active below 15°C. The upper
limit (i.e. 35°C) is imposed by in-
activation of many green algal species.
If the temperatures in facultative ponds
exc,eed 35°C, more volume must be pro-
vided or the system cooled mechanically.
INDUSTRIAL CASE HISTORIES
To illustrate the adaptability of
pond systems, performance data from
four waste stabilization pond systems
representing an aggregate of over
10 years of operating experience and
corresponding receiving water data
are described. For comparative purposes,
data from five activated sludge treatment
plants treating mixtures of chemical and
petroleum refining wastes, data from a
special bench-scale study comparing
activated sludge with waste stabilization
pond performance, and data from exemplary
plants in the Organics Chemical Develop-
ment Document are utilized to compare
the performance levels attainable by the
two types of treatment systems (U.S.
EPA, 1, 1974).
a. WSP Treatment Systems
Geographically, three of the indus-
trial plants are located along the
coastal areas of Texas, Latitude 29°
and the fourth is about 400 km north.
There is an abundance of sunshine and the
annual precipitation varies from about 90
to 132 cm per year. The mean annual
temperature (MAT) for the coastal area is
about 21°C (12°C, coldest month) and
for the northern site the MAT is 19°C
(8.5°C, coldest month).
A variety of organic chemicals are
produced and one plant also includes
a petroleum refining operation. A
comparison of manufacturing and waste
treatment operations is presented in
Table 1.
The four large waste stabilization
pond systems evaluated in this study
demonstrated the following:
(1) The highest long-term average
effluent 5-day BOD concentration was
38
-------
25 mg/1, including the algal cells in the
effluent. The total influent BOD was
reduced 98 to 99 percent by the three
waste stabilization pond systems treating
wastewaters from organic chemicals
manufacturing complexes. BOD removal for
the system tre.ating mixed petroleum
refining and organic chemical wastewaters
was 88 percent, reflecting the lower
influent BOD concentration by this
system.
(2) The four waste stabilization
pond .-systems for which total organic
carbon (TOO effluent data were available
removed greater than 83 percent of the
influent TOC on an average basis. The
highest long-term average effluent TOC
concentration for all four waste stabili-
zation pond systems was less than 80
mg/1.
(3) Long-term average effluent COD
concentrations from the three for which
data were available were less than 160
mg/1.
(4) As expected, the presence of
algal cells results in relatively
high total suspended solids (TSS) concen-
trations in the waste stabilization
pond effluents. The long-term average
effluent TSS concentrations are as high
as 100 mg/1, although they exhibit marked
variability depending upon the specific
characteristics of each pond system. In
contrast to the TSS in high-rate biologi-
cal treatment plant eflfuents, the
majority of the TSS in pond effluents are
algal cells.
(5) An extremely important charac-
teristic of waste stabilization pond
performance is the stability of opera-
tion. Maximum effluent variability
expressed as the ratio of the maximum
daily concentration to the long-term
average concentration was low for BOD,
COD, and TOC with the highest ratio
recorded being 3.1 and with most daily
variability ratios being in the range of
2.0 to 2.5. The variability of TSS was
somewhat higher, reflecting algal growth
in the waste stabilization pond systems.
Notwithstanding this, the highest ratio
of daily TSS concentrations to long-term
average was 3-2.
b. WSP Data Analysis
Because the Guidelines of the U.S
Environmental Protection Agency (EPA)
were developed on a basis of a treatment
facility designed to achieve a long-term
average effluent loading, it was neces-
sary to relate the effluent variability,
both for the daily and monthly limits, to
the long-term arithmetic average effluent
quality. The methodology followed for
the variability analyses was identical to
that used by EPA, as presented in the
Development Document for the Petroleum
Refinery Point Source Category and its
Supplement (EPA, 2, April 1974, and EPA,
3, April 1974). The basic procedure
involved the following: 1) The effluent
concentration data for each plant in-
cluded in the investigation was plotted
on log-normal probability paper; 2) the
line of best fit representing approxi-
mately the upper 60 percent of the
expected daily and monthly variations was
determined for each plant considered; 3)
a daily variability factor was defined as
the ratio of that effluent concentra-
tion encompassing 99 percent of the
expected daily variation to the long-term
arithmetic average effluent concentra-
tion; .and 4) a monthly variability was
defined as the ratio of that effluent
concentration encompassing 98 percent
of the expected monthly variation to the
long-term arithmetic average effluent
concentration.
Table 2 summarizes the case history
data for the four waste stabiliza-
tion pond treatment facilities. The
effluent quality from the waste stabi-
lization ponds in terms of BOD is com-
parable to other biological treatment
processes. However, COD and TOC reduc-
tions obtained by pond systems are often
much better. This is attributable to the
extended hydraulic detention in pond
systems which provide the microorganisms
sufficient time to degrade the more
refractory compounds. Residual organics
may be readily measured by COD or
TOC tests, but short-term BOD tests may
not provide accurate information.
The variability of TSS in these effluents
represent the algal growth cycles which
occur as a function of incident solar
energy and climatological phenomena.
The variability factors summarized
in Table 2 are attempts to account
for the "inherent variability" in the
long-term average effluent concen-
tration from a properly designed and
operated waste treatment plant. The
term "inherent variability" is defined as
that variance in effluent quality
attributable to the basic nature of the
treatment processes, the character-
istics of the wastewater, and the clima-
tological conditions—none of which
can be significantly altered by external-
ly applied changes. The published
EPA effluent limitations are based on
maximum allowable daily and monthly
average discharges. Because treatment
system design and performance analysis
has been on more of an "average" or
steady-state basis, it becomes mandatory
to consider the variability in the
treatment system's effluent quality
in order to determine its compliance with
the federal limitations.
39
-------
Table 1. Industrial waste stabilization pond systems.
Subject
Itemization
Major Production
Pond System
1. Mech. Aerated
2. Anaerobic
a) 1st Stage
b) 2nd Stage
(addl. proc.
water,
neut., etc.)
3. Facultative
Discharge
Characf prizaf inn of Industry and Treatment Plant
A
Ethylene
Proplene
Acetylene
Ethyl Benzene
Ethylene Oxide
Ethylene Glycol
Axo-Alcohols
Amino
Polyols
Styrene
Butadiene
Cellulose
Acetate
No. = 1
Ar. = 3.2 ha (7
Deten. = 1 d
Depth = 2.5 m
No. =5 para.
Ar. = 16.2 ha
(40 ac)
Deten. = 50 d
No. = 1
Ar. = 56.7 ha
(140 ac)
Deten. = 60 d
Depth = 1.5 m
No. = 1
Ar. = 118 ha
(291 ac)
Deten. = 68 d
Depth = 1 m
Continuous
Barge Canal
B
Olefins
Ethanol
Acetyldehyde
Ethylene Glycol
Oxo Chemicals
Polyproplene
Polyethylene
-0-
.8 ac)
No. = 7 ser.
Ar. = 25 ha
Deten. = 60 d
Depth = 2 m
-0-
No. = 2 ser.
Ar. = 174 ha
(430 ac)
(180, 250)
Deten. = 180 d
Depth = 1-2 m
Seasonal-winter
Oxygen sag
Control in river
C
Hexane
Cyclohexane
Benzene
Toluene
P-Xylene
0-Xylene
Paraffins
Propylene
Isobutylene
Naptha
Ethane
Ethylene
Solvents
Motor Fuel
Lubricants
-0-
-0-
-0-
-0-
No. = 3 ser.
Ar. = 142 ha
(350 ac)
(175, 70, 105)
Deten. = 14 d
Depth = 1.3 m
Continuous
brackish
water
D
Polyethylene
Ethylene Vinyl
Acetate
Copolymer
High Density
Polyethylene
Adiponitrile
Hexamethylene-
diamlne
Ethylene
Methanol
Adipic Acid
Hydrogen
Cyanide
Nitric Acid
Ethylene
Cogolyners
-0-
No. = 1
Ar. = 16.2 ha
(40 ac)
Deten. = 30 d
Depth = var.
No. = 1
Ar. = 2.2 ha
(5.5 ac)
No. = 1
Ar. = 51.4 ha
(127 ac)
Deten. - 17 d
Depth = 1 m
Continuous
River
Treatment Parameter
Effluent
BOD5 (mg/1)
COD (mg/1)
TOC (mg/1)
TSS (mg/1)
Average Monthly
BODS (7»)
COD (%)
TOC (%)
24(1. 8)a
158(1.4)
101(1.9)
80(1.5)
Removal
98
93
89
99(2.4)
--
93(2.1)
8(1. 6)a
97(1.3)
37(1.3)
26(1.8)
92
68
59
16(2. l)a
__
29(1.6)
80(2.7)
98(2.1)
—
93. (2. .7.)
Variability factor.
40
-------
Table 2. Summary of waste stabilization pond treatment performance in the organic
chemicals and petroleum refining industries.
Plant
BOD
COD
TSS
TOC
Var.
Ratio
Var.
Ratio
Long-
term
Var.
Ratio
Long-
term
Day Mo. Av. Day Mo. Av. Day Mo
Max. Av. Cone. Max. Av. Cone. Max. Av. Cone. Max. Av.
Long-
term
Av.
Var.
Ratio
Long-
term
Day Mo. Av.
Cone.
(mg/1)
(mg/1)
(mg/1)
(mg/1)
A
B
C
D
EPA BPT Guidelines: &
Organ. Chem, Indus. ^
Petrol. Ref. Indus.
2.4
3.1
1.8
-
4.5
3.2
1.8
2.4
1.6
2.1
2.0
1.7
24
15
8
16
20-30
15
2.5
2.0
1.4
-
_
3.1
1.4
2.0
1-3
_
1.6
158
134
97
Varies
80-110
3.2
2.6
2.2
-
4.5
3.3=
1.9
1.9
1.8
2.7
2.0
2.1C
101
46
26
80
30
10
2.0 1.5
2.1
1-3
1.6
-
_ *~
80
56
37
28
-
""
aAs amended 5/12/76 (40 CFR 414, 41 FR 19310), Remanded 4/1/76 (40 CFR 414, 41
FR 13936).
^Data from 308 Questionnaire raw data summary sheets, January 1975 through
September 1976.
CAS amended 40 FR 21939, 5/20/75.
Note: BOD = Biochemical Oxygen Demand, 5-day, 20°C;
TSS = Total Suspended Solids;
Var = Variability; Day = Daily; Mo. = Monthly; Av. = Average Max. = Maximum;
Cone. = Concentration.
There are several points which
should be kept in mind when considering
the variability of the effluent quality
from any particular treatment system.
In general, as the effluent concentration
or loading from a treatment system
is decreased, the effluent variability
expressed as a ratio increases. This
phenomenon is primarily due to the fact
that the distribution of effluent concen-
trations or loadings is bounded at the
lower end by the non-removable portion of
a particular constituent and by the
sensitivity of the analytical tests
involved. There is no similar boundary
on the upper end of effluent concentra-
tions. For example, a 15 mg/1 variation
in BOD when the long-term effluent
concentration is 15 mg/1 variation
represents a variability factor of 2.0,
whereas the same 15 mg/1 variation
represents a variability factor of 4.0 if
the long-term average is 5.0 mg/1.
Another observation concerning the
variability factors developed as a result
of this study is the fact that the choice
of a variability factor encompassing 99
percent of the expected variation implies
that the maximum daily effluent loading
predicted on this basis may be expected
to be exceeded 1 percent of the time.
Likewise, the maximum monthly average may
be exceeded 1 month out of every 50
months of operation if the 98 percentile
is used. Such occurrences are inherent
in a probabilistic approach to effluent
variability and present no major problems
with respect to design, provided they are
properly considered. Variability anal-
yses are shown in Figures 2 through 5.
c. WSP Model
Typical treatment models have been
developed for these pond systems and the
presentation is in general accordance
with the format used in the U.S. EPA
Development Document. These models
should not be used for general design
purposes for these observations apply
only to a unique grouping of industrial
wastewaters, climate, and operations.
Only one example (FWSP) is presented
herein:
Facultative Waste Stabilization Pond
(FWSP) - ("Aerobic" under EPA definition,
FutTn reality this is a misnomer.)
4L
-------
8-5,10
h- E
o 0,01
1 i !
_m 1 i
L_*_ ,
-_4_i_
4 «
M-:
ht~
'
-
;
-
'•'I*
j* 1 [—- <—t . 1
—
_
. —
_ ..
-
.-
—
'D/
VI
r-
i
I
1
vr
u
A
.UE
— 1
•
=TS.= AVG.
I IN GROUf
3
10 50 90 99 9999
PROBABILITY
10
'DATA PTS. = AVG
VALUE IN GROUP -
Q
001 I 10 50 90 99 99.99
PROBABILITY
Figure 2. Daily maximum variability Figure 4. Daily maximum variability
analysis, analysis.
Q .001 I 10 50 90 99 99,99
PROBABILITY
Figure 3- Daily maximum variability
analysis.
! ALL AVERAGES ARE
MONTHLY AVERAGES
JJ I
10 50 90 99 99.99
PROBABILITY
Figure 5. Monthly averge variability
analysis.
EFFECTIVENESS:
BOD Removal:
Percentage removal
depends upon design.
Soluble BOD5 in ef-
fluent is less than
10 mg/1 in most ap-
plications. Total ef-
fluent 8005, includ-
ing TSS contribution
due to algal cells, is
less than 25 mg/1
long-term average.
E ff iue£_t_BOD5 : Long-term average
"soluble fraction
approaches 10 mg/1.
Suspended solids
fraction is approxi-
mately 0.2 kg of
BOD5 per kg TSS in
the effluent.
Phenol Removal: Greater than 99
percent of phenolic
material is re-
moved at specified
design criteria.
42
-------
Phenol in effluent
is less than 0.1 mg/1
long-term average.
Oil Removal: Oil removal is greater
than 90 percent.
Attainable effluent
concentration is less
than 5 mg/1. It
should be noted that
chlorophyll in algal
cells will be me a-
sured in most oil and
grease analyses.
COD, TOC, and TOD Removal: Up to 90
percent TOC removal,
has been obtained,
depending on design of
system. When preceded
by anaerobic or
mechanically aerated
lagoons, typical per-
formance is 45 to 80
percent TOC removal.
COD and TOD removal
data are not as com-
plete as for TOC,but
indicate that a con-
servative assumption
is that COD and TOC
removals are equal to
TOC removal. When
used as a polishing
step behind activated
sludge, ponds are
usually not designed
for TOC removal
greater than 50 per-
cent. It should be
emphasized that the
above removals are
on a total TOC, COD,
and TOD basis, and
include the contri-
bution of algal cells
to effluent organic
concentrations.
APPLICATION LIMITS:
PH
Temperature
5-10
>55°F
(Annual mean
daily minimum
temperature as
presented in
the Decennial
Census of U.S.
Climate, U.S.
Weather
Bureau)
Oil £35 mg/1
TDS £10,000 mg/1
TSS £125 mg/1 (annual average)
Sulfates £1,500 mg/1
Sulfides <200 mg/1
OPERATING BASIS:
BOD5 Removal:
Se = 0.?3 (S0/t) + 0.43 (L) + 1.0
in which
Se = effluent BOD^ concentration
(soluble and solids), mg/1
So = influent BOD^ concentration
(soluble and solids), mg/1
t = hydraulic detention time, days,
and
L = surface loading, kg BOD^/ha/day
(Ib BODc/acre/day)
S0 £ 3,500 mg/1
t >_ 10 days
L £ 67 kg BOD5/ha/day (60 Ib
BOD5/acre/day)
TOC Removal:
Se = S0 [(1) - [13.5 Uoge t)
- 0.1 (L)
10]/[100]
in which
Se= effluent total TOC
concentration (soluble
and solids), mg/1,
S0 = influent total TOC
concentration (soluble
and solids), mg/1,
t = hydraulic detention time,
days, and
L = surface loading, kg
TOC/ha/day
S0 £ 2,000 mg/1
t > 10 days
L £ 50 kg TOC/ha/day (45 Ib
TOC/acre/day)
Effluent TSS (predominantly algal
cells):
Xe = 32 (loge L) + 27 doge t) - 100
in which
Xe = annual average effluent
TSS, mg/1,
L = surface loading, kg
BOD5/ha/day, and
t = hydraulic detention time,
days
L £ 112 kg BOD5/ha/day (100
Ib BOD5/acre/day)
t > 10 days
Effluent Soluble Organics:
Soluble BOD5 = Se(total BOD5)
- 0.2 Xe
Soluble TOC = Se(total TOC)
- 0.2 Xe
Soluble COD = Se(total COD)
- 0.9 Xe
43
-------
TEMPERATURE:
Within the specified temperature
application criterion, these specific
design equations do not need to be
corrected for winter conditions. The
water temperature in these ponds will be
essentially the same as monthly average
temperature. (Note: This specific
temperature criterion is not general
because colder, seasonal temperatures
may control pond designs.)
COST PARAMETER:
Flowrate.
COST CURVE SCALE FACTOR:
Surface loading of 600$ or TOC.
RESIDUES:
Solids accumulation is low if
specified influent TSS requirement
is met. It can be assumed that 30 cm of
depth will provide over 10 years of
solids storage.
MAJOR EQUIPMENT:
FWSP Ponds—In these examples
parallel construction with equal distri-
bution of volume is generally used.
Construction:
Inlets/Outlets:
Nutrient Storage
and Feed:
Operating depth
1 to 2 m plus
0.5 m of solids
storage; dikes with
side slopes between
1 to 3 (vertical to
horizontal) and 1 to
6, top width 6 to 8
feet; freeboard 1 m
above maximum water
level; erosion pro-
tection; permeabil-
ity of bottom and
sides less that
10~5 cm/sec.
Gravity flow,
submerged outlet or
provides with baffle
and weir. Splitter
box is required.
As required.
d. WSP Comparison with
Activated Slud~ge
The waste stabilization pond perfor-
mance data described above were compared
with long-term operating records obtained
from five activated sludge plants treat-
ing similar wastewaters and one set of
detailed laboratory studies. These data
were obtained and evaluated in order to
provide a better data base than was
available from the Organic Chemicals
Development Document which was used by
EPA to establish the remanded organic
chemicals effluent guidelines. Com-
parison of the waste stabilization pond
performance data summarized above with
the long-term operating data from these
activated sludge plants, data from the
Organic Chemicals Development Document,
and bench-scale treatability data for
the wastewaters from one of the partici-
pating plants in this evaluation demon-
strates the following:
(1) Total BOD removals, including
the suspended solids contribution, by the
waste stabilization pond systems are at
least as good as,, if not better than, the
high-rate biological treatment systems.
(2) The long-term average effluent
concentrations of refractory organic
materials (COD and T.OC) in the waste
stabilization pond system effluents are
50 percent less than the corresponding
values for the high-rate biological
treatment systems.
(3) The variability in effluent
quality from the waste stabilization pond
systems is lower for all waste constitu-
ents, including total suspended solids,
than the high-rate biological treatment
systems.
(4) The average effluent TSS
concentration from the waste stabili-
zation pond systems is higher than the
corresponding value from the five
activated sludge case histories, but
lower than the effluent TSS values
exhibited by the exemplary plants in
EPA's Organic Chemical Development
Document.
(5) Overall, the performance of the
waste stabilization pond systems treating
organic chemicals and petroleum refinery
wastewaters equals or, as in the case of
TOC and COD, exceeds performance exhibit-
ed by high-rate biological treatment
systems. The only possible exception
to this is effluent TSS concentrations
which consist principally of algal cells
in the waste stabilization pond ef-
fluents. It is thus important to con-
sider the impact of these algal cells on
receiving waters to demonstrate any
necessity for removing algae before final
discharge. Table 3 summarizes various
comparisons.
Bench-scale studies conducted with
wastes from Plant B provided the data
44
-------
Table 3- Comparison of activated sludge and waste stabilization pond effluents.
BOD COD
Rem.
Av.
Effl.
Cone.
(mg/1)
Day
Max.
Var.
Mo.
Av.
Var.
Rem.
Av.
Effl.
Cone.
(mg/1)
Day
Max.
Var.
Mo.
Av.
Var.
Waste Stabilization Pond:
Plant A
Plant B
Plant C
Plant D
98
99
92
98
24
15
8
16
2.4
3.1
1.8
-
1.8
2.4
1.6
2.1
93
_
68
_
158
134
97
_
2
2
1
.5
.0
.4
-
1.4
2.0
1-3
-
Activated Sludge:
Case 1
Case 2
Case 3a
Case 4b
Case 5
Bench Scale,
EPA Exemplary
EPA Exemplary
EPA Guidelines:
Organ. Chem.
Organ. Chem.
Petrol. Ref.
Petrol. Ref.
Plant
B
Plants (All)
Single-stage
Indus.
Indus.
Indus.
Indus.
-BPTC
-BATC
-BPT
-BATC
_
_
_
_
-
97
93
Plants 92
-
_
_
-
34
16
24
15
16
30
82
-
20-30
20-30
15
5
6.6
18.9
3.0
4.0
2.8
_
-
-
4.5
3.9
3.2
2.1
2.2
3.0
1.7
2.0
2.1
_
-
-
2.0
2.1
1.7
1.7
_
_
_
_
-
79
74
69
_
_
_
-
334
229
333
110
237
396
378
-
Varies
Varies
80-110
20-27
2
8
2
1
2
3
3
2
.5
.7
.0
.8
.4
_
-
-
-
.9
.1
.0
1-3
1.7
1-3
1.6
1.8
-
-
-
-
2.1
1-6
1-6
alncludes refining wastewaters.
^Hybrid plant, i.e., biological and clean stream effluents combined in holding/polish-
ing pond before final discharge.
cRemanded by Federal Courts by EPA.
Note: BOD = Biochemical Oxygen Demand, 5-day, 20°C;
COD = Chemical Oxygen Demand;
Av. = Average; Day - Daily; Mo. = Month; Effl. = Effluent; Max. = Maximum;
Rem = Removal; Cone. = Concentration; Var. = Variability.
shown in Table 4. Note that after 24
hours, there was little improvement in
the soluble organic quality attainable by
the activated sludge system. Also, the
data show the impact obtainable through
the use of anaerobic and facultative
ponds. Removals of BOD as high as 97
percent were obtained with an influent
BOD of nearly 1,000 mg/1. COD and TOC
removals were also high at 79 and 80
percent, respectively.
It is particularly important to note
that the TSS concentrations used by the
EPA to define 1977. Effluent Limitations
for the Organic Chemical Industry were
exceeded by the vast majority of the
exemplary plants used by the EPA in their
analysis. The TSS concentrations in the
pond effluents, consisting mainly of
algae, are consistent with those that
were obtained in the EPA survey, but are
not consistent with the limitations that
were finally established in the Effluent
Guidelines.
EMPIRICAL DESIGNS
During the last decade, various
authors have reported on the performance
of various pond systems (Stander and
Meiring, 1962; Aguirre and Gloyna, 1970).
While some observations have been based
on long-term studies, many conclusions
appear to have been based on relatively
short term tests. Because of the long-
term detention, environmental effects
and cyclic characteristics of algae, it
is important to base conclusions on
fairly lengthly studies. Important design
parameters must include information on
variability of waste characteristics,
environmental factors, and effluent
requirements.
The literature contains many refer-
ences to FWSP designs, including general-
ization based on population served per
volume, fixed detention and organic load
per surface area. Interestingly, while
the pond system is exceedingly complex,
experience in pond design based on a
45
-------
Table 4. Activated sludge treatment of
wastewater from Plant B.
Detention Time
One- Two- Three-
Initial Day Day Day
MLSS, mg/1 4,070 4,520 4,620 4,470
MLVSS, tng/1 3,040 3,540 3,580 3,390
COD, mg/1 1,674 432 444 470
TOC, mg/1 600 110 120 155
given geographical area and wastewater
may produce best treatment results.
Clearly, major factors important in
the design of a FWSP must include the
total BOD (soluble and settleable load),
flow, temperature (based on average
temperature of most critical month, hot
or cold), light (although a precise
knowledge of the total flux is academic),
total potential sulfide concentration,
and an understanding of potential
for chlorophyll inhibition (Gloyna,
1971) .
One empirical relationship for
design of facultative ponds has been
developed over years of laboratory, pilot
plant, and field experience. An example
follows:
Given:
A biodegradable wastewater:
8005 influent, 20°C
BOD,, influent
= 250 mg/1
= 305 mg/1
Reaction coefficient (Base e)
= K20oC = 0.35 day-1
Flow = 7.57 x 10° cu I/day (2 x 106
gal/d) (U.S.)
Design temperature
= 25°C (average coldest month)
Assume:
1. Evaporation rate = rainfall
2. Percolation rate = negligible
3. Sunlight = usually sunshine
4. No chlorophyll inhibition
problems, f - 1 (Huang and
Gloyna, 1968)
5. Sulfates < 500 mg/1, f = 1
(Gloyna and Espino, 1969)
6. Solids typical of domestic
wastes
Required:
Calculations showing (a) organic
load, (b) volume, (c) depth, (d)
surface area, (e) detention, and (f)
sur face
1.085.
Solution:
(a) Organic Load = (305 mg/1) (7.57 x
106 cu I/day)
= 2309 kg BOD/d (5091 lb
BODu/day)
(b) Volume = 3.5 x 10-5 QL
[1.085(35-1)] (l) (l)
= (3,5 x 10-5) (7.57 x
106) (305) [1.085<10>]
= (3.5 x 10-5) (7.57 x
106) (305) (2.26)
= 183,000 cu m (148 acre
ft) exclusive of
sludge storage)
(c) Depth (Use) = 1.25 m (4.1 ft)
(d) Surface Area = 18.3 ha (45.2 acres)
(based on 1 meter
effective depth and
0.25 m sludge storage)
(e) Detention = 24 days (based on 1
meter effective depth)
(f) Surface
Loading = (2309 kg/day)/(18.3 ha)
= 126 kg BODu/ha per day
(112 lb BODu/acre per
day)
The BODc removal efficiency can be
expected to be 80 to 90 percent or bet-
ter. The efficiency based on unfiltered
effluent samples can be expected to vary
unless a maturation pond is used as a
follow-up unit.
The detention time provided by the
above equations is given in Figure
6. Added detention times may be provided
by increasing the depth, but this extra
depth must not be used to calculate the
surface area.
The minimum depth of about 1 meter
is required to control potential growth
of emergent vegetation. If the depth is
too great, there will be inadequate
surface area to support photosynthetic
action. Deep ponds tend to stratify
during hot periods. The following design
guidelines for depth are suggested:
CASE DEPTH
1 1 meter
RELATED CONDITIONS
loading for BOD,, if =
Generally ideal con-
dition, very uniform
temperature, tropical
to subtropical, minimum
settleable solids.
2 1.25 meters Same as above but with
modest amounts of
settleable solids.
Surface design based on
1 m depth and 0.25 m
used for sludge. (For
wastes containing
considerable amounts of
biodegradable, settle-
able solids, the FWSP
should be preceded
by an anaerobic pond.)
46
-------
WHERE t0= 7.0 DAYS
T = TEMR-AVO. COLDEST MONTH
D ¥ DAYS
S.= INFLUENT BOD
0
5 10 15 20 25
TEMPERATURE (°C)
Figure 6. Detention for facultative
waste stabilization pond.
3 1.5 meters
1.5 to 2
meters and
greater
Same as Case 2 except
for significant season-
al variation in tem-
perature, major
fluctuations in
daily flow. Surface
design based on L m of
depth.
For soluble wastewaters
that are slowly biode-
gradable and retention
is controlling.
Surface design based on
1 of depth.
WSP IMPACT ON WATERWAYS
There are three processes that have
to be considered in examining the effect
of pond algae on a receiving water.
First, over a relatively long time
period, some of the pond algae will die
and exert an oxygen demand on the oxygen
resources in the receiving stream over a
large segment of its length. Second,
introduced algae will adjust their
generation rates within a matter of days
to reflect the new set of environmental
constraints and exert a negligible demand
on the oxygen resources on the receiving
body of water. Third, the resident algal
populations may reflect a downstream in-
crease in size as a function of nutrient
loadings, if the receiving system is not
light-limiting at the autotrophic level.
Ample evidence indicates that place-
ment of algae into a dark environment
does not cause their immediate death.
Rather, algae die at a diminishing
rate and require 20 to 30 days to deplete
their nutritional reserves. Studies
indicate that at least some cells of
C^hilor^lj.^ and S cje ri^d^e ss mujs remained
suFFrcFently via¥le to Fe recultured
after 60 to 90 days in an unheated
anaerobic digester (Golueke, Oswald, and
Gotaas, 1957).
The most common cause of algal death
in effluents derived from FWSP occurs
during the chlorination process. It has
been shown that it is ppssible to chlo-
rinate at a dosage to kill IE. coli and
permit survival of certain algae. The
maximum dosage permissible for algal
survival appears to be about 8 to 10
mg/1. Above this dosage, lysis of algal
cell increases and the BOD of the ef-
fluent increases accordingly (Horn,
1968).
The respiration requirements of
viable algae are only about 3 percent
of the body weight. If algae discharged
to a stream remain suspended in light and
are supplied the needed nutrients, they
will grow and produce excess oxygen in
the absence of severe salinity and
temperature stresses. Data collected by
Plant A illustrate that the algae can
withstand major changes in salinity and
temperature. If the algae settle out,
they will respire at a low rate, with
oxygen demands of dead algae being
approximately 1.4 times the dry weight of
freshly destroyed algal cells.
Algae are important natural resi-
dents of stabilization pond effluents,
as well as the receiving waters into
which they are discharged. Analyses
substantiate that in a properly designed
and operated pond system, algal cells in
the effluent do not constitute a signi-
ficant impact on the dissolved oxygen
resources of the receiving waters.
Furthermore, algae usually serve as an
important link in the receiving water
food chain. Discharge of algal cells in
a properly treated effluent may increase
productivity at higher trophic levels of
aquatic organisms of economic importance,
for example, fin fish, shrimp and crab in
estuarine environments. Therefore, algae
do not appear to effect most receiving
waters in a deleterious manner and
their removal from a highly treated
effluent should not be required unless
studies of the receiving waters prove
this step to be necessary.
The removal of algal cells from pond
effluents has been studied in consider-
able detail (Middlebrooks, 1974; Parker,
1976; Dinges, 1978; and Bare, Jones, and
47
-------
Middlebrooks, 1975). The removal systems
include the use of predators and water
hyacinth cultures, air flotation, sand
filtration, rock filtration, and nutrient
control.
ECONOMIC CONSIDERATIONS
While the operational efficiency of
certain pond systems in terms of attain-
able effluent quality characteristics can
be clearly demonstrated, there are
factors which support the implementation
of these systems as B£^s^t_P_r_ac^t_i£j:il_
Control Technology Currently Available
a n d / o r B e^s Jt_££jij?enj; io^na_!_P_p_l 1 u t; ja rrt_
£^£^££J:_J_^^F^oTo£y""Fo"F'~:fl-¥¥tment of
municipal wastewaters and certain indus-
trial waste streams. Table 5 shows
estimated energy requirements for two
"high-rate" biological treatment systems,
an aerated lagoon, and a waste stabili-
zation system, all designed to meet the
same effluent BOD for a given influent
condition. The analysis excludes any
waste pretreatment requirements and
tertiary treatment. Pretreatment needs
are essentially the same for each case,
although the activated sludge system
would require equalization. The waste
stabilization system is more economical
than the other biological treatment
systems in all respects, and the energy
savings are substantial. If electricity
is provided by a fossil-fuel-fired power
plant, the energy saved by a waste
stabilization pond, as compared to an
activated sludge plant, for the example
in Table 5 represents about 136 tonnes
Table 5. Comparison of energy require-
ments for biological treatment
systems.a
Treatment
Type
Energy Use
(kwh/yr)b
Activated Sludge 1,000,000
Aerated Lagoon 850,000
Rotating Biological Contactor 120,000
Waste Stabilization Pond -0-
aBasis:
1. Flow - 3,785 cu. meters per day (1
million gallons U.S. per day).
2. Influent BOD5 - 350 mg/1 (2,900
pounds per day).
3. BOD removal rate - 0.001 mg/1 per
day.
4. Excludes pumping and pretreatment
costs.
^To convert from kilowatt hour to
joule, multiply by 3-6 x 10°.
(150 tons) per year of coal. If equal
COD or TOC removal were used as the
design criterion, then the energy re-
quirements would be much higher for
the other systems treating a refractory
chemical wastewater since considerable
additional hydraulic detention time (or
disk area in the case of the rotating
biological contactor) would have to be
provided. Similarly, if lime is used to
assist certain chemical treatment re-
quirements, about 6.3 kilojoules ( K 6
million Btu) will be needed to produce a
1,000 kg of lime.
Biological treatment processes
operate at peak performance levels
when the volume and composition of
influent wastewaters are kept constant.
This is particularly true in the treat-
ment of organic chemical wastewaters
which are highly variable in quantity and
quality and which .can be very detrimental
to continuous operation of a high-rate
biological treatment system. Because of
this, all BPCTCA type biological systems
which rely on high-rate biological per-
formance require considerable equaliza-
tion capacity to assure that shock
loadings are minimized. Wastewater
stabilization ponds provide considerably
more equalization and their large volumes
can accept short-term fluctuations and
shock loads with much greater efficiency
than can the high-rate biological systems
(Gloyna, Herring, and Ford, 1970). Waste
stabilization pond systems which are used
in the organic chemicals industry
generally provide a residence time of 100
days or more. Retention times for
equalization of this order of magnitude
cannot be economically provided in
the typical high-rate biological waste
treatment system.
SUMMARY
Wastewater stabilization ponds, when
properly designed and operated, and when
located in a region with a climate suit-
able to their maximum efficiency of oper-
ation, provide effluent quality evels of
treated organic wastewaters completely
consistent with Best Practicable Control
Technology Currently Available as defined
by the EPA in their Development Documents
for both the Organic Chemicals and
Petroleum Refining industries. In fact,
the soluble BOD removals of refractory
COD are often considerably better
for a well-operated and well-designed
wastewater stabilization pond system
than those obtainable using high-rate
biological treatment facilities. The
major problem which accrues with waste-
water stabilization ponds is in meeting
the total suspended solids limitations
established by the applicable Effluent
Guidelines.
48
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The engineering approach to the
solution of any problem must take
into account the technical alternatives.
In a WSPS design, it is necessary
that each facility be a custom design
having adjustments for many factors
associated with a local situation.
Properly designed and applied integrated
WSPS will permit maximization of the
reclamation potential for both waste-
water and nutrients.
REFERENCES
1. Aguirre, J. , and E. F. Gioyna.
1970. Design Guidelines for Biologi-
cal Wastewater Treatment Processes--
Waste Stabilization Pond Per-
formance. Report No. 77, Center for
Research in Water Resources, Univer-
sity of Texas at Austin, Austin,
Texas 78712.
2. Bare, W. F., W. B. Jones, and E.
J. Middlebrooks. 1975. Algae Re-
moval Using Dissolved Air Flotation.
Journal Water Pollution Control,
Vol. 47, p. 153-
3. Dinges, R. 1978. Upgrading Stabi-
lization Pond Effluent by Water
Hyacinth Culture. Journal Water
Pollution Control, Vol. 50, No. 5,
p. 833-845.
4. Engineering-Science, Inc. 1977-
Effectiveness of Waste Stabilization
Pond Systems for the Treatment of
Organic Chemicals and Petroleum
Refinery Wastes. Report Presented
to U.S. Environmental Protection
Agency.
5. Gioyna, E. F. 1971. Waste Stabi-
lization Ponds. 175 p., Monograph
No. 60, World Health Organization,
Geneva, Switzerland.
6. Gioyna, E. F., and E. Espino. 1969.
Sulfide Production in Waste Stabi-
lization Ponds. Journal of the
Sanitary Engineering Divisison,
American Society of Civil Engineers,
Vol. 95, No. SA 3, p. 607-628.
7. Gioyna, E. F., M. Herring, and D. L.
Ford. 1970. Treatment of Complex
Petrochemicals by Incineration and
Waste Stabilization Ponds. 2nd
Annual Purdue Industrial Waste
Conference, Lafayette, Indiana.
8. Gioyna, E. F., J. F. Malina, Jr.,
and E. M. Davis, Editors. 1976.
Ponds as a Wastewater Treatment
Alternative. p. 447, Center for
Research in Water Resources, The
University of Texas at Austin.
9. Golueke, C. G., W. J. Oswald, and H.
B. Gotaas. 1957. Anaerobic Fer-
mentation of Algae. Applied Micro-
biology, Vol. 5, p. 47-55.
10. Horn, L. H. 1968. Differential
Chlorination of Waste Pond Ef-
fluents. Ph.D. Dissertation, Univ-
ersity of California at Berkeley,
Berkeley, California.
11. Huang, J., and E. Gioyna. 1968.
Effect of Organic Compounds on
Photosynthetic Oxygenation. Part 1
and 2, Journal Water Research, Vol.
2, 5, and 6, p. 347-66, p. 459-69,
Pergamon Press, Great Britain.
12. Ichimura, S. 1968. Phytoplankton
Photosynthesis. Algae, Man and
the Environment, edited by D. F.
Jackson. Syracuse University
Press.
13. Middlebrooks, E. J. 1974.. Upgrad-
ing Wastewater Stabilization Ponds
to Meet New Discharge Standards.
Symposium Proceedings, PRWG159-1,
Utah Water Research Laboratory, Utah
State University, Logan, Utah.
14. Oswald, W. J. 1963. Waste Treat-
ment by Oxidation Ponds. Symposium,
Central Public Health Engineering
Research Institute, Nagpur, India.
15. Oswald, W. J. 1976. The Fate of
Algae in Receiving Waters. Ponds
as a Wastewater Treatment Alter-
native, p. 257-276, Center for
Research in Water Resources, The
University of Texas at Austin.
16. Parker, C. D. 1976. Pond Design
for Industrial Use in Australia
with Reference to Food Wastes.
Ponds as a Wastewater Treatment
Alternative, p. 285-299, Center for
Research in Water Resources, The
University of Texas at Austin.
17. Parker, D. S. 1976. Performance of
Alternative Algae Removal Systems.
Ponds as a Wastewater Treatment
Alternative, p. 401-417, Center
for Research in Water Resources, The
University of Texas at Austin.
18. Stander, G. J., and P.G.J. Meiring.
1962. Health Aspects of Maturation
and Stabilization Ponds. Pretoria
(£SI_j?_£e_p£J.jit._^W_lJ37.) ; Public
Health, Vol. 63, 5-15, Johannesburg,
South Africa.
19. U.S. Environmental Protection
Agency, 1. April 1974. Development
Document for Effluent Limitations
Guidelines and New Source Perfor-
49
-------
mance Standards for the Major mance Standards for the Petroleum
Organic Products Segment of the Refining Point Source Category.
Organic Chemicals Manufacturing Washington, D.C.
Point Source Category. Washington,
D.C. 21. U.S. Environmental Protection
Agency, 3. April 1974. Suplement B
20. U.S. Environmental Protection to the Development Document for
Agency, 2. April 1974. Development Effluent Limitations Guidelines for
Document for Effluent Limitations the Petroleum Refining Point Source
Guidelines and New Source Perfor- Category. Washington, D.C.
50
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DESIGN AND CONSTRUCTION OF WASTEWATER STABILIZATION PONDS
Earl C. Reynolds, Jr. and
Scott B. Ahlstrom*
In late 1967, construction was
completed on a centralized sewage treat-
ment facility for the City of Logan,
Utah, consisting of a series of stabili-
zation ponds and a chlorination struc-
ture. Design and services during con-
struction on this project were accom-
plished by CH2M HILL. This presentation
will discuss CH2M HILL'S experience in
the design and construction of stabiliza-
tion pond systems. Our purpose will be
to identify particularly critical problem
areas; and some of the techniques that
CH2M HILL has utilized to solve these
problems.
This discussion on stabilization
pond design and construction will focus
on the Logan system. This is appropriate
since the ponds serve our hosts, the City
of Logan and Utah State University.
Participants at this conference may have
an opportunity to view these stabiliza-
tion ponds during their stay in Logan.
Experience from other stabilization pond
systems also will be utilized to illus-
trate design and construction practices.
The first step in the design of a
waste treatment facility involves es-
tablishing the proper design criteria.
Many of the design parameters pertaining
to wastewater stabilization ponds are
established by state or other regulatory
agencies. This presentation will briefly
identify some of these standards,
but will be directed principally to
stabilization pond design and construc-
tion as experienced by CH2M HILL.
REGULATORY STANDARDS
Design standards are formulated by
regulatory agencies to ensure that the
"Earl C. Reynolds, Jr., is Vice
President, and Scott B. Ahlstrom is
Wastewater Reclamation Engineer, with
CH2M Hill, Boise Office, Boise, Idaho.
design of sewage treatment systems is
consistent with U.S. Public Health and
water quality objectives. The Ten-State
Standards have formed the basis for
regulatory agency design criteria for
stabilization ponds for a number of years
and have done so quite satisfactorily.
They provide guidance in numerous areas
including design loadings, physical
location, hydraulic capacity, and
construction details. The Utah state
standards are similar in some respect,
although they do depart in significant
instances from the Ten-State Standards.
Some of the principal points covered
under the Utah state standards are as
follows:
Isolation, or the necessity for
the treatment facility to be
set apart from habitation and
water supply sources.
Number and size of the stabili-
zation pond compartments with
due consideration given to
loading, effluent disinfection,
and future population growth.
Embankment and dike design,
construction, and protection.
Pond bottom treatment to
provide for suitable drainage,
uniform depth, and leakage
prevention.
Inlet and outlet structures
which minimize short circuiting
and prevent leakage.
Flow measurement.
The U.S. EPA and the Federal Water
Pollution Control Acts (PL 92-500 and PL
95-217) also affect the design and
construction of wastewater stabilization
ponds. Specific procedures must be
complied with in order to obtain a
federal construction grant. Furthermore,
federally approved discharge standards
must be satisfied.
51
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DESIGN AND CONSTRUCTION
This discussion of stabilization
pond design and construction has been
organized into the following principal
elements.
Site Reconnaissance
Geotechnical Investigation
Aeration
Layout
Earthwork
Dike Protection and Seepage
Control
Hydraulics
Structures, and
Leakage Test
Site Reconnaissance
The fact that a stabilization pond
is built principally from materials
available at the selected site focuses
particular attention on site selection.
Land availability and land suitability
must be assessed. Topographical features
should be observed and undesirable
geological characteristics such as basalt
outcrops, granular alluvial deposits, and
limestone formations noted. The site
should be relatively flat and the soil
preferably should be a fine textured,
clayey type rather than coarse granular
material. One extremely important factor
which must be considered is the avail-
ability of the land, and the ability to
obtain it without arousing the concern of
surrounding property owners. Ideally,
the site should be located below the
city, close to a receiving stream, safe
from flooding, and available for purchase
at a reasonable cost.
Based on the information gathered
during the site reconnaissance regarding
land availability, topography, geology,
and other miscellaneous inputs, a pre-
liminary site layout can be developed.
The site selected for the Logan
stabilization ponds is located in the bed
of the ancient Great Salt Lake—an
excellent location for a facility of this
type. Approximately half of the site was
farmed. The other half consisted of
hummocky marshland utilized for late
summer pasture.
Geotechnical Investigation
After developing a preliminary site
layout, confirm that suitable soil
conditions exist. Test pits and borings
should be strategically located and soil
samples obtained. Laboratory tests
conducted on the soil samples must
determine physical classification,
strength, and permeability. From this
information, a subsurface profile is
developed and geological conditions are
confirmed. Sources of materials for
lining, riprap, and embankments should
also be located.
The geotechnical investigation at
Logan identified the material at the site
as a highly plastic clay. Although a
500-acre site was involved, very few test
holes were required due to the general
uniformity of the geological conditions
over the bed of the ancient Great
Salt Lake. In other less uniform sites a
test hole every acre may be far from
adequate. For example, in Idaho a
stabilization pond was recently con-
structed on a site which was under-
lain with fractured and highly pervious
basaltic lava flows. A great deal of
difficulty was encountered during con-
struction because the undulating nature
of the surface of the lava flows had not
been adequately identified. Rock
was encountered during excavation,
causing substantial cost over-run and
raising difficult questions concerning
prevention of leakage.
In parts of the country, sites
suitable from a topographical standpoint
are underlain with limestone which is
subject to caverns and fissures, which
serve as underground conduits. In these
cases a thorough geological study would
be a necessity.
In other instances, and this is not
unusual in the arid west, we have found
that layers of caliche underlie many of
the suitable sites. In one instance, we
determined that this caliche would cause
great difficulties if a winter storage
lagoon for an industrial waste treatment
operation were constructed. The indus-
trial waste would become anaerobic during
winter storage, and seepage of the an-
aerobic fluid from the pond would be
expected to dissolve the caliche, en-
dangering the embankment structure
and/or causing large-scale leakage.
Once the geotechnical engineering
has been completed, a final location for
the stabilization pond can be recom-
mended. An integral part of this recom-
mendation involves choosing a site
which complies with the governing state
regulations. If the site recommended
satisfies the desires of the community, a
final site layout is developed and the
land acquisition process set in motion.
The site selected for Logan was west
of town and involved about 1 1/2 miles of
interceptor sewer to conduct the waste
from the city to the stabilization ponds.
By elevating the interceptor sewer on a
compacted berm, all of the waste from the
City of Logan could reach and pass
through the ponds by gravity. Ideal soil
52
-------
conditions on the site indicated that
potential pond leakage would be minimal.
Not only was the soil adequate to seal
the ponds, but the aquifer beneath the
ponds existed under a positive hydro-
static head. Two flowing artesian wells
had to be plugged at the site prior to
construction.
Aeration
Aerobic and facultative ponds may
derive the oxygen necessary for proper
operation from natural or mechanical
means. Under natural means, dissolved
oxygen is furnished by oxygen transfer
between the air and water surface and
by photosynthetic algae. The amount of
oxygen supplied by natural surface
reaeration depends largely on wind-
induced turbulence—a supply mechanism
usually neglected in design because of
its lack of dependability. The primary
source of natural aeration is from algal
photosynthesis. The photosynthetic
production of oxygen is cyclic. During a
sunny day the liquid contents of a
shallow lagoon will become supersaturated
with oxygen. Photosynthesis ceases at
night, but respiration continues, re-
sulting in an increase in carbon dioxide
and a decrease in oxygen concentra-
tion.(1)
In a mechanically aerated lagoon the
major portion of oxygen transfer is
caused by the aeration device. Two basic
methods of aerating sewage are (1) to
agitate the sewage mechanically at the
surface so as to promote solution
of air from the atmosphere, or (2) to
introduce air or pure oxygen into the
sewage with submerged porous diffusers or
air nozzles.
In the case of surface aerators, the
units can be either fixed-mounted or
float-mounted. In fixed-mounted units,
the vertical support columns can be
constructed of concrete pipe, steel
beams, wood piling, and even bridge-
mounted when the width is within prac-
tical limitations. Fixed-mounted units
should have adjustable baseplates or
other methods for varying the submergence
of the rotor. Very frequently, surface
aerators for large aerated waste stabili-
zation basins are f1oat-mounted .
This has the advantages of allowing
fluctuations in liquid level and ease of
repositioning (or removing entirely) the
aerators. Also, in most cases, a more
economical installed cost may result.
(1)
A diffused air system consists of
diffusers submerged in the sewage, header
pipes, air mains and blowers. Diffused
air systems are much more suitable in
climates where extended periods of
freezing occur.
Layout
The layout of a stabilization pond
system is greatly influenced by the shape
of the site acquired. A good layout will
minimize the quantity of earthwork
required and maximize flexibility of
operation. The pond layout should
include common dike construction, rounded
pond corners to prevent collection of
floating materials, and multiple cells to
minimize short circuiting.
Since the Logan ponds are of sub-
stantial size, it was felt necessary and
desirable to provide two systems oper-
ating in parallel, with some common
facilities in the last three cells
(Figure 1). The design provides for
operating the ponds with any one cell out
of service for an extended period of
time. Note that a total surface area of
458 acres, and a storage capacity of over
3,000 acre feet is required to serve the
City of Logan.
During normal operation, the ponds
are designed for a combination of paral-
lel and series operation; i.e., the flow
is equally divided at the distribution
structure and directed to Ponds A-j and
A2, which discharge into Ponds B-) and
83, respectively. Ponds BI and 82 dis-
discharge into Pond C and the combined
flow continues through Ponds D, E, and
the chlorine contact basin. Ponds
A-| , A2, BI, and 82 serve to expose a
large surface of the raw sewage to both
air and sunlight. This exposure promotes
growth of algae and other forms of life
which utilize nutrients in the sewage for
growth. Ponds C, D, and E serve prima-
rily to provide detention for the sewage
after treatment in 'Ponds A-|, A2, BI,
and 82. As there is normally no nutrient
supplied to these ponds from the raw
sewage, the algae population will
usually be reduced. The detention time
provided by these ponds is also suffi-.
cient for a large portion of the coliform
bacteria in the sewage to die. Since
these ponds were built some 10 years ago,
it has generally been found that the
coliform requirements of the Utah State
Division of Health then in effect
could be met without chlorination. The
chlorination facilities provided at the
Logan ponds have only been used during
test periods.
Figures 2 through 5 describe the
performance of Logan's stabilization
ponds over a 5-year period. The effluent
BOD has ranged from 31 mg/1 to 1 mg/1
53
-------
with 90 percent of the values less than
18 mg/1. Effluent TSS have been less
than or equal to 30 mg/1 90 percent of
the time. Extreme values have varied
from 100 mg/1 to near zero. Ninety
percent of the total coliform counts have
numbered less than 1000/100 ml. Values
as high as 11,500/100 ml and as low
as zero have been recorded. The maximum
fecal coliform count recorded was
1100/100 ml. Minimum values have reached
zero or none detected. Fecal coliform
counts have numbered less than or equal
to 300/100 ml for 90 percent of the
measurements.
Earthwork
The earthwork techniques utilized in
constructing a wastewater stabilization
pond are generally identical to those
used in constructing an earth dam.
Vegetation and porous topsoils should be
stripped from the pond site. Any sand or
gravel pockets should be removed and
the subsoil compacted. The pond embank-
ments should also be adequately compacted
during construction to provide stability
and to prevent seepage. It may be
necessary to sprinkle fine-grained
materials in order to obtain the optimum
-EFFLUENT CANAL
FOR IRRIGATION BY
LOCAL LANDOWNERS
48" INFLUENT
SEWER
"•EFFLUENT CANAL
TO LOGAN RIVER
ARROWS INDICATE DIRECTION
OF NORMAL FLOW.
POND
A1
A2
B!
B2
C
D
E
TOTALS
SURFACE AREA
(acres)
94
94
70.5
70.5
63
38
28
458
DEPTH
(feet)
6.0
6.0
6.7
6.7
7.35
7.9
8.5
VOLUME
(acre feet)
564
564
472
472
463
300
238
3073
Figure 1. Logan wastewater stabilization ponds.
54
-------
soil moisture content which will yield
the maximum soil density.
After the pond dikes have been
adequately compacted, they must be
trimmed to the specified slope. Exterior
slopes should accommodate mowing equip-
ment for ease of maintenance. Interior
slopes vary according to the type of
soil available and the erosion protection
provided. Figure 6 shows the construc-
tion of the Logan stabilization ponds and
the procedure the contractor used to trim
the dikes after placing and compacting
the material.
Earthwork design also includes the
development of roadways or access ways on
top of the dikes. On smaller facilities
we have utilized a roadway as narrow as 8
feet, but with ponds as large as those
for Logan, greater widths are advisable.
The roadways should be graveled to
allow access under wet weather condi-
tions.
For the most economical construc-
tion, excavation should be designed to
balance with fill. Since the Logan pond
site consisted largely of 3 to 4 foot
hummocks, it was extremely difficult to
® EFFLUENT SAMPLES TAKEN B.Y LOGAN
EFFLUENT SAMPLES TAKEN BY
UTAH STATE DIVISION OF HEALTH
! = : 1"? ! i i t s I 5 I s i 1 i ! I s I i
li II Hi!
1974 1975
Figure 2. Performance of Logan wastewater stabilization ponds--effluent BOD vs,
time (1971-1975).
55
-------
determine an average or typical eleva-
tion. Photogrammetry was used to develop
a 50-foot grid of spot elevations. Even
with this complete topographical data,
obtaining a balance of cut and fill was
difficult, since a difference of 0.1 foot
elevation was equivalent to about 80,000
cubic yards of material at the Logan
site.
We established a construction
procedure to permit a balance of cut and
fill. It called for stripping the
primary and secondary ponds, filling the
low spots with the strippings, and
then excavating to a predetermined bottom
elevation to obtain material for con-
struction of the berm under the influent
pipeline and for certain pond dikes.
Upon completion of excavation in these
cells, adjustments were made in the
bottom elevation of the final ponds so
that the required excavation quantities
could be obtained. This procedure worked
very satisfactorily.
•5,
g, EFFLUENT SAMPLES TAKEN BY LOGAN
A EFFLUENT SAMPLES TAKEN BY
UTAH STATE DIVISION OF HEALTH
&
&
15 i I i i n = m i 111 i t in i j * I'i iltn ''•• tt'tTlii lljjf
1971 1972 1973 1974
• i is I 11 \ I it s\
Figure 3. Performance of Logan wastewater stabilization ponds--effluent TSS vs
time (1971-1975).
56
-------
An additional consideration af-
fecting earthwork is the location of
groundwater. At Burley, Idaho, we are
involved in upgrading the existing
stabilization pond by installing an
aerated pond and a pH adjustment cell.
Construction of the pH adjustment cell
involved excavating to a depth con-
siderably below the groundwater table.
In this case, it was necessary for the
contractor to dewater the area by well
points before he could properly construct
the new cell.
t
11,600
Dike Protection and Seepage
Control
The protection of earth dikes
against wave action and maintenance of a
relatively water-tight seal throughout
the stabilization pond are major design
considerations. Our experience has
indicated rather conclusively that dikes
forming ponds larger than 10 to 15 acres
should be provided with protection
from wave erosion. In one of our early
projects, a 65-acre facility for the
t
I 7.600
1800
I
5 1600
a.
o
5 1000
© EFFLUENT SAMPLES TAKEN BY LOGAN
A EFFLUENT SAMPLES TAKEN BY
40 UTAH STATE DIVISION OF HEALTH
®
©
©
© ^SS»
sHi tlliif SHHl tlii!
1971 1972
A
©
.1 i i s i I \ \ I s i
1973
i \ I.I I i
1974
1 \ H i i
197S
Figure 4. Performance of Logan wastewater stabilization ponds—effluent total
coliforms vs. time (1971-1975).
57
-------
City of Ontario, Oregon, slope protection
provided in the initial design consisted
only of locally available pitrun gravel,
generally under four inches maximum size.
During a rather violent thunderstorm in
the second year of its operation, wave
development was sufficient to cause
serious erosion damage to the downwind
dikes. Emergency riprapping was required
to save the dikes. Riprap has subse-
quently been provided for the remainder
of the pond.
In areas where a prevailing wind
exists, it may be permissible to place
the heavier riprap on the downwind dikes
only; and provide lighter protection on
the dikes which are not subject to severe
wave action. This can result in con-
siderable cost savings.
Figure 7 is an illustration of a
relatively small pond that experienced
severe interior dike erosion because
proper slope protection was not provided.
I:
•: ; : .-':..
:::••:
.: : ; - ; :
i; ; i ; 1 i ; ; ! i
;;; i V.f
_ , . . .
1 i M ; ] \ ] \ \ \
':'::•': \ \ \ \ \
: : : : ; : : : : :
MM: M"M !
: : : : : : : : r :~
•t I- i !• • I : • •
: . j-- :
inn!
5 m C (^ * 0
a 3 & g fi H
1971
; ; : ; i ; ; ; ; ;
I L I ! I •::::!
" ; : : "• .:. i i- i '.
© EFFLUENT SAMPLES TAKEN BY LOGAN
A EFFLUENT SAMPLES TAKEN BY
UTAH STATE DIVISION OF HEALTH
: : : : : ; i .:.•::-
'. ': ': 11 1 ! I : \ \
:'.','.'. : ' ' ' :
. ; : . r J_ : - i : : : : :
;. j .....
: --;- *• ; ' I - - - -
; : • : : l ' ' : ^
• : ' : : i
A
: ; '• ' :J_; ;.; -:.i
- i ; i I i ;• : i :
— ;-; H-
: ' .
u;" ::-7-i
r. ; r ' v i : ; : i: ': •
' : : : : !:•;;. .:!. .:
•;:•-•_(_; iri.r-i '
: : i ; : i : ; : : :
; : . . ; I - : . -
... : •-•;..::.
:
& A. A4\
i
A >C
l ' ] . :
,® A
:-;:=!- -••=: : - : -
• . : : '• \ : : : . , | . . . : . . :
.::::!
i i H i ! i i I § i i
1972
; ' (Si
; : . : - i^ :
: : ' : • •
1 i H i * i ! 1 i i H 5 H 1 1 1 ! a I 1 i
1973
1974
I 5! 5 I ! i 11 si 1
1975
E
8
ec
o
IL
3
U 300
Figure 5. Performance of Logan wastewater stabilization ponds—effluent fecal
coliforms vs. time (1971-1975).
58
-------
Figure 6. Trimming dikes at the Logan
wastewater stabilization ponds.
Figure 7. Erosion of interior dike sur-
face at a wastewater stabili-
zation pond in Greenville,
Michigan.
In addition to protection of the
interior surfaces of the dike, it is
necessary to protect the exterior dike
surfaces from erosion due to runoff and
wind. We frequently place topsoil on
exterior slopes and seed the slopes with
a suitable variety of native grass. In
semiarid areas typical of much of the
Intermountain West, dryland grasses such
as crested wheat have survived well
without irrigation.
In some instances where mechanical
aeration is involved, it may be necessary
to provide a layer of gravel, or a
concrete pad, of sufficient size on the
bottom of the pond to prevent scour due
to the velocities developed by the
aeration equipment.
At Logan, a relatively heavy riprap
was used to protect the interior dike
slopes. The need for the heavy riprap
resulted from the steep interior slopes,
potential high wind velocities, and the
large "fetch" common in ponds of this
size. The slope of the dike directly
affects the amount of wave energy
absorbed, and the energy of the water
scouring the face of the dike. A more
gradual slope lessens the effect of the
waves. However, flat slopes provide
shallow areas ideal for emergent vegeta-
tion .
Figure 8 shows a typical section of
the dikes constructed at Logan. A 0.8
foot gravel filter was placed on the
compacted dike and overlaid with 1 foot
of quarried riprap. The exterior surface
was seeded with a mixture of 60 percent
tall wheat grass and 40 percent crested
wheat grass. The dikes are of sufficient
height to allow a 3 foot freeboard.
At some installations, it may be
necessary to lower the phreatic surface
or water table within the exterior dikes
to provide embankment stability and to
control seepage at the exterior toe. A
6" ROCK BASE
SEEDED WITH
TALL WHEAT GRASS AND
CRESTED WHEAT GRASS
RIPRAP
FILTER GRAVEL
Figure 8. Method of dike protection at the Logan waste stabilization ponds,
59
-------
filter blanket similar to that shown in
Figure 9 is excellent for such condi-
tions.
Seepage control is also required
around any pipeline penetrating a dike.
Concrete collars have been utilized to
prevent erosion and to reduce the likeli-
hood of seepage along the pipeline.
Proper installation of pipes passing
through dikes can be assured by building
up the dike at least 2 feet above the
pipe elevation, then cutting a trench for
the pipe. The trench should be filled
and compacted with an impervious back-
fill.
Some of the alternatives available
for controlling seepage in stabilization
pond bottoms are identified in Figure 10.
This figure also illustrates the general
effectiveness of each approach as com-
pared to the cost. The use of con-
crete, asphalt, and soil cement is
limited to special situations due to
their high cost. Soil sealing chemicals
and bentonite find limited application
due to their low effectiveness. If
suitable materials are available, it
is our preference to use an earth blanket
for sealing the pond bottom. However, the
use of any pond liner must be evaluated
according to the specific site require-
ments. If the ponds are to remain empty
for a prolonged period, considera-
tion must be given to the possible
effects from freezing and thawing during
cold weather or cracking from hot, dry
weather. Freezing and thawing will
generally loosen a soil liner for
some depth. We recommend maintaining an
adequate volume of water in earth-lined
all times to prevent breakup of
bottom. The liquid depth should
sufficient to prevent weed
Roots from weeds can form
in the pond bottom.
ponds at
the pond
also be
g rowth.
conduits
When suitable materials are not
available or suitable conditions do not
exist for earth blankets, synthetic
membranes such as PVC are commonly
used.
FILTER BLANKET
Figure 9. Dike section showing filter blanket installation.
HIGH
COST
LOW
HIGH
IEFFECTIVENESSI
LOW
Figure 10. Relative cost/effectiveness of various pond liners.
60
-------
Although these membranes are effec-
tive sealants, special installation
procedures are required to prevent damage
to the membrane. We recommend the use of
a minimum 20 mil thickness to minimize
the danger of puncture. It is necessary
to support the membrane with a care-
fully prepared granular material. We
also consider it necessary to cover the
membrane after installation to hold it in
place and provide additional protection.
This covering should c6nsist of fine-
grained materials which, in turn, may
require a covering of well-graded
gravel or some other material that is
sufficiently heavy to prevent erosion of
the fine material that protects the PVC
liner.
We have had some unhappy experiences
with PVC lining. Early in the history of
aerated ponds, some manufacturers of this
material felt it was unnecessary to cover
the lining after installation. We cannot
recommend that practice.
Hydraulics
In smaller ponds, the inlet struc-
ture normally consists of a single
influent pipe which terminates near the
center of the pond. Design conditions at
Logan indicated that a more complex
structure was necessary. Since these
ponds are very large, it was considered
essential to utilize a full scale dif-
fuser to distribute the influent over a
large area of the primary cells and to
minimize short circuiting. Furthermore,
Logan experiences extremely high seasonal
variations of flow due to summer in-
filtration of irrigation water. A dual
diffuser was selected to handle these
variations in flow.
Figure 11 shows a plan view of the
Logan diffuser. The inlet was designed
so the majority of the wastewater solids
and influent flow would always be handled
by the main diffuser. This reduced the
potential for solids buildup within the
•diffusers and around the diffuser
outlets. When the influent flow exceeds
the capacity of the main diffuser, the
influent overflows into the secondary
diffuser. An inlet pad common to the
main and secondary diffusers prevents
scouring of the pond bottom. A typical
diffuser outlet used at Logan is shown in
Figure 12.
Flow measurement is commonly ac-
complished by the use of a parshall
flume. Because the throat width is
constant, the discharge can be obtained
from a single upstream measurement of
depth. Flow measurement allows the
operator to control the pond system for
optimum treatment of the wastewater.
Structures
Correctly designed inlet, transfer,
and outlet structures are the keys to
proper hydraulic operation of stabiliza-
tion ponds. Influent structures should
properly distribute the wastewater flow
to diffusers or inlet pipes. Pond
transfer structures should be valved or
provided with other arrangements to
regulate flow between ponds and permit
variable depth control. Scum baffles and
stop-log guides should be provided on
structures between ponds that have a
potential for undesirable floating
debris. The pond effluent structure
should be equipped with multiple drawoff
lines or some other adjustable drawoff
POND A?
DIFFUSER N0.1
2 3 4 5
234
DIFFUSER NO. 2
Figure 11. Diffuser and distribution box layout at the Logan wastewater stabiliza-
tion ponds.
61
-------
Figure 12. Typical diffuser outlet at
Logan ponds.
device, so effluent can be withdrawn from
selected depths. Under normal operation
the lowest drawoff lines should be high
enough above the pond bottom to prevent
eroding velocities and avoid picking up
bottom deposits. Provisions should also
be included to allow for drainage of the
pond.
Since a stabilization pond is
frequently inviting to trespassers, it is
also recommended that a fence and warning
signs be placed around the perimeter of
the pond advising of the pond contents.
Leakage Test
In our opinion, newly constructed
ponds should be subjected to a leakage
test, except in rare instances. A
leakage test was not conducted at Logan
because of the relatively impervious soil
conditions, and the artesian aquifer
beneath the site. Ponds in areas where
surrounding homes draw their water supply
from wells should always be tested.
The amount of actual leakage from
stabilization ponds may be difficult to
determine. At a facility with a large
surface area, evaporation becomes very
significant and must be taken into
account when calculating the pond seepage
rate. Our estimate of average evapora-
tion at Logan during summer months was on
the order of 1 cubic foot per second. We
estimated the average annual evaporation
at 0.5 mgd. In our opinion, regulations
that specify a seepage rate less than 1/4
inch per day for earth ponds are un-
realistic. First, actual evaporation
from the pond surface cannot be calculted
accurately enough to determine such low
seepage rates. Secondly, it is doubtful
that earth-liners are capable of pro-
viding a sufficiently tight seal to yield
seepage rates below 1/4 inch per day,
especially under a high head.
CONCLUSION
Our experience with the many types
of treatment facilities has convinced us
that a properly designed and constructed
stabilization pond is a highly reliable
and effective form of waste treatment.
The key to designing and constructing a
successful facility lies in performing
the various design elements with the
same care that would be utilized on a
large earth dam.
REFERENCES
(1) Wastewater Treatment Plant Design,
prepared by a joint committee of
the ASCE and WPCF, Lancaster Press,
Inc., 1977.
• -'
-------
A CASE HISTORY EXAMINATION OF
LAGOON UPGRADING TECHNIQUES
L. Sheldon Barker*
There are many cities in the south-
ern Idaho, eastern Oregon, and northern
Utah areas using stabilization ponds to
treat their wastewater. Most of these
ponds were built in the 1960s and now
need some form of effluent upgrading to
meet current Environmental Protection
Agency (EPA) requirements for secondary
treatment. CH2M HILL has had the op-
portunity to complete "201" facilities
plans for several towns with lagoon
facilities including: La Grande, Baker,
and Ontario, Oregon; Burley, Idaho; and
Logan, Utah. All of these cities have
flows exceeding 1 million gallons per day
(mgd) which places them in the top 5
percent of communities using lagoon
treatment(1) .
The EPA has established secondary
treatment requirements whereby towns
with design flows in excess of 2 mgd
must meet the following effluent quality:
1. Biochemical Oxygen Demand (BOD)
< 30 mg/1.
2. Total Suspended Solids (TSS) <
30 mg/1.
3. The treatment facility must
provide a minimum removal of 85 percent
of the influent BOD and TSS.
Wastewater lagoons, by themselves,
will not meet these treatment require-
ments, principally because of the large
suspended solids load contributed by
algae growth in the ponds. Lagoons
offer advantages, however, that amply
justify their continued use, even though
algae removal processes must follow.
Lagoon treatment provides:
1. Simple operation almost totally
free of operational control requirements.
*L. Sheldon Barker is P.E., CH2M
Hill, Inc., Boise, Idaho.
2. Stable operation that has a
low probability of malfunctioning. This
stability applies both to the biological
processes, where the large volume of a
lagoon provides tremendous buffering
capacity against organic shock loads, and
to mechanical simplicity. Mechani-
cal equipment used with lagoons is
limited principally to pump stations and
aeration equipment.
3. A very low energy requirement,
again due to the general lack of mechani-
cal equipment necessary to operate
lagoon.
4. An ability to convert ammonia
to nitrate. A well designed lagoon will
achieve almost total biological conver-
sion of ammonia to nitrate, a more
innocuous form of nitrogen.
When secondary treatment standards
were first promulgated for wastewater
lagoons, back in the early 1970s, there
were few proven methods for polishing
lagoon effluent. Only chemical addition
(alum) and clarification followed by
dual media filtration had at that time
been operated successfully, at a 0.5 mgd
facility in Lancaster, California (2).
The other method then available for
meeting discharge requirements was land
disposal, using lagoon effluent directly
without the need for further treatment.
Some of the other alternatives being
investigated at that time included:
chemical addition followed by dissolved
air flotation, mixed media filtration,
intermittent sand filtration, anaerobic
rock filters, and microstraining.
Even the two proven polishing
techniques were not without drawbacks.
Chemical addition and clarification or
dissolved air flotation requires ex-
pensive doses of alum and polymer to
coagulate the single cell algae species
present in wastewater lagoons. In
addition, this alternative requires
operator sophistication and attention.
Land treatment is a relatively simple
technical alternative, but is often
63
-------
administratively difficult to imple-
ment. Land treatment requires large
acreages of contiguous property which
can be difficult to obtain, as many
existing property owners may be in-
volved. Irrigation districts may be
persuaded to accept lagoon effluent
but very often the farm community is
reluctant to accept the crop restric-
tions that many states place on the
use of this water.
More recently, treatment alterna-
tives are under development which show
promise of upgrading lagoons while main-
taining their traditional advantages
of simplicity and stability. Micro-
straining is an example of recent tech-
nological advancement. Polyester fabric
has been produced reducing the sieve
size available to 1 micron, much below
the 23 micron stainless steel screens
that were previously available.
The evolution of lagoon upgrading
technology is perhaps best understood
by examining case histories of cities
and the treatment alternatives which
they tested and selected. The three
case histories of lagoon upgrading
presented in this paper are:
1. Ontario, Oregon--Pilot testing
of phase isolation.
2. La Grande, Oregon--Selection
of air flotation and filtration.
3. Burley, Idaho—Pilot testing
of microscreening and aquaculture.
ONTARIO, OREGON
The City of Ontario has a four
pond, series lagoon system with pond
sizes of 45 acres, 23 acres, 9-5 acres,
and 9.0 acres followed by chlorination.
The system has an average annual
flow of about 1.7 mgd and must be up-
graded to meet secondary standards.
Figures 1 and 2 show various pond treat-
ment efficiencies. Note that the ef-
fluent violates TSS requirements.
The facilities plan (3) originally
proposed chemical addition and sedi-
mentation as the cost effective treat-
ment alternative, after jar tests in-
dicated alum would be an effective algae
coagulant. The city's primary concern,
however, was to minimize operation and
maintenance costs. They decided to
investigate further a less proven treat-
ment alternative: phase isolation.
With assistance from CH2M HILL, Ontario
removed Pond No. 3 (see Figure 3) from
their lagoon treatment scheme and set
up a phase isolation pilot test program
modeled after the successful Woodland,
California, operation (4). Initially
the program was delayed while excessive
leakage in Pond 3 was corrected using
betonite. The phase isolation pilot
test has been running since March 1977.
Results of the program are shown in
Table 1. The middle column of Table 1
indicates the minimum holding time in
the isolation pond required to produce
a secondary treatment quality of 30
mg/1 BOD and TSS. This holding time
is important as the primary design
factor for a phase isolation system.
Since testing was not done daily, the
residence times are probably somewhat
higher than the absolute minimum re-
quired. Two conclusions can be drawn
from these data:
1. The minimum isolation times
varied from run to run without an easily
Table 1. Ontario, Oregon, phase isolation program.
Run
No.
Approx.
Date
Earliest
Isolation Time
To Meet Secondary
Treatment
Lagoon Quality Obtained
at the Specified
Isolation Time
BOD,-
TSS
1
2
3
4
5
6
7
8
March 1977
August 1977
September 1977
December 1977
January 1978
February 1978
March 1978
June 1978
7 days
28 days
21 days
28 days
a
12 days
17 days
b
20 mg/1
18 mg/1
5 mg/1
18 mg/1
44 mg/1
27 mg/1
16 mg/1
21 mg/1
18 mg/1
27 mg/1
19 mg/1
16 mg/1
40 mg/1
30 mg/1
17 mg/1
34 mg/1
aPond No. 3 did not meet secondary treatment during a 28-day holding period.
Pond No. 3 did not meet secondary treatment during a 40-day holding period.
64
-------
discernible pattern. Selecting an
isolation time for use as a design
parameter would be difficult.
2. Secondary treatment was not
achieved on 25 percent of the runs, even
after isolation periods of up to 40
days.
The winter of 1977 had above normal
temperatures in eastern Oregon so the
pond never developed its usual extensive
ice cover. Operating personnel reported
that the ice which did occur minimized
the treatment capability of phase isola-
tion.
Phase isolation does not seem able
to produce a satisfactory level of treat-
ment for Ontario, especially since the
State of Oregon, Department of Environ-
mental Quality (DEQ) water quality guide-
lines could eventually require a summer-
time BOD and TSS effluent of 20 mg/1.
Phase isolation may, however, provide
a -benefit to those smaller cities which
have been granted a suspended solids
waiver and, therefore, are not required
to completely meet secondary treatment
standards.
LA GRANDE, OREGON
The City of La Grande has a two cell
lagoon system with a total surface area
of 100 acres. Selection of the cost ef-
fective method to upgrade treatment for
210
dfe
n =
Q_I
§u.
u.
0. Ill
dfc
n™
Q_l
Zu.
O U-
CLUI
SAMPLE POINTS
Figure 1. Variations in COD, TSS, VSS, and BOD5 through the wastewater lagoon sys-
tem, 18-20 November 1974.
65
-------
this community of 11,000 was complicated
by several factors:
1. The existing discharge into
Gekeler Slough (a tributary of the Grande
Ronde River) cannot continue because
there is no dilution water available
during the summer and fall. Ice block-
age has also caused downstream flooding
during the winter.
2. The Grande Ronde River, the
alternate discharge point, offers more
flow, but is almost 5 miles from the
existing lagoon site. Even this re-
ceiving stream has low summer flows and
the DEQ is requiring the following
dilution restriction:
(BOD5)(Effluent Flow)
(Receiving Stream Flow)
< 1
3. The city sewer system is old
and suffers from infiltration, especial-
ly during winter months. Not all the
infiltration is cost effective to re-
move, thus the 85 percent secondary
treatment requirement often requires
an effluent quality substantially be-
low 30 mg/1.
Table 2 predicts the cumulative
discharge requirement that La Grande
will have to meet at the Grande Ronde
River. The dilution governing effluent
criteria in Table 2 were based on aver-
age summer water flows in the Grande
Ronde River and low water years will
impose even more stringent effluent re-
quirements. The upgrading alternative
must be capable, therefore, of producing
a 10 mg/1 effluent quality for BOD and
TSS. This severely restricted the al-
ternatives available.
18
•a.
CC
UJ
u
8
TOTAL
ELDAHL
TROGEN
AMMONIl
NITROGE
2U. Qu.
111 O.U1
SAMPLE POINTS
n =
2s!
Ouj
Figure 2. Nitrogen balance through the wastewater lagoons, 18-20 November 1974.
66
-------
FOND A/O. 3
OLITLGT
•KIP KAf=>
f OM GAST
I SIDE Of=
MALHEU'K, DK.IVK
~DiK.e ACCESS.
Figure 3- Phase isolation pilot study-site plan.
-------
Table 2. La Grande, Oregon, required ef-
fluent quality.
Month
January
February
March
April
May
June
July
Augus t
September
October
November
December
Maximum
BOD &
TSS
20 mg/1
17
18
20
27
27
30
14a
16a
12a
30
30
Limiting Factor
85 Percent Removal
85 Percent Removal
85 Percent Removal
85 Percent Removal
85 Percent Removal
85 Percent Removal
Secondary Treatment
Dilution Requirement
Dilution Requirement
Dilution Requirement
Secondary Treatment
Secondary Treatment
Based on summer flow in the Grande
Ronde River during average water years.
Jar tests with alum were run on the
lagoon effluent. Although the algae
flocculated very well, it maintained a
neutral buoyancy. The floe appeared to
be buoyed by small trapped gas bubbles,
even though the jar tests were performed
in the dark to eliminate continued 02
production. A hypothesized explanation
is that the algae had supersaturated
the pond with oxygen and that this
oxygen came out of solution in the
rapid mix portion of the jar test.
Because of the buoyancy condition,
the feasibility of using clarification,
such as was done in Lancaster, Califor-
nia, did not appear favorable. Air
flotation was the superior choice.
Filtration was added following the air
flotation to polish the effluent and
produce the required treatment. A
moving bridge backwash filter (such as
manufactured by Environmental Elements
Corporation) was selected for its low
head requirement. This eliminated the
need for an intermediate pump station.
The facilities plan (5) indicated
that upgrading the lagoon in the manner
shown in Figure 4 was the cost effective
solution. Design criteria developed for
this alternative are shown in Table 3-
Construction bonds for the existing
lagoo.n have almost been paid for and the
facility does not warrant abandoning in
favor of an activated sludge facility.
Land application of lagoon effluent was
examined closely since the Grande Ronde
valley is a strong agricultural area.
Freezing winter conditions and high
spring groundwater severely limited the
application season, and ultimately led
to a prohibitively high alternative
cost.
Even after the facilities plan
had been adapted, the city remained
quite concerned about the necessity
of discharging directly to the Grande
Ronde River with an effluent pipeline
to be built at an estimated cost of
$650,000. A new alternative was de-
veloped using the existing discharge
at Gekeler Slough as a receiving stream
during the winter and as an irrigation
canal during the summer. To use Gekeler
Slough as an irrigation canal the city
had to guarantee that there would be no
discharge from Gekeler Slough into the
Grande Ronde basin during the summer
irrigation season. This alternative
also included a small fall storage pond
to handle effluent during fall months
(after the irrigation season) until
adequate dilution flows become available
again in Gekeler Slough.
Summer irrigation discharge was an
attractive alternative to the city. Con-
struction of the effluent pipeline would
not be necessary and a lower quality ef-
fluent would be allowed during the summer
moriths, thus reducing operation costs for
power and chemicals. Implementation of
this alternative required that an irriga-
tion district be formed to distribute
water among the area farmers. The dis-
trict would contractually agree with the
city to handle all their summer flows
over the next 20 years. Oregon water
right laws complicated the formation of
the district because:
1. Water rights existed on the
lagoon effluent which was then being
used for irrigation.
2. The oldest water rights en-
titled its holders to use lagoon ef-
fluent, whether they belonged to the
district or not.
3. Farmers without water rights
were afraid that if they joined the
district, while those with older water
rights did not, the only time they would
get any water would be in wet years.
During those times they would be forced
to take water they didn't need, and
their crops would be damaged as a
result.
Legal evaluation of the district
formation required, therefore, that
participation by all 13 area farmers
would have to be unanimous.
The City of La Grande tried for 9
months to help get the irrigation dis-
trict formed. Several public meetings
were held and three different draft
agreements between the city and the
irrigation district were prepared. Even
in the drought year of 1977, the farm-
68
-------
LAGOON EFFLUENT
FLOW CONTROL &
MEASUREMENT
AIR FLOTATION
FLOAT COLLECTOR
POSSIBLE
Clj
ADDITION
GRAND RONDE
RIVER
Figure 4. Schematic diagram: lagoons/chemical treatment/filtration.
-------
ers never agreed to the district for-
mation, principally because:
1. There was still concern over
the winter flood potential in Gekeler
Slough.
2. The DEQ required the farmers
to limit to non-human consumption the
types of crops they could grow.
3. Water is still relatively
plentiful in the Grande Ronde basin and
the farmers preferred to be independent.
The city decided that the only
viable alternative was to build the
pipeline to the Grande Ronde River.
Ironically a portion of this pipeline
crosses a farm whose owner is requiring
up to 500 gpm of summer flow (for his
irrigation) as a condition of his pro-
perty easement. The city is in the
process now of checking other farms
along the pipeline right-of-way to see
if there is further interest in using
this water for irrigation. The advantage
in this case is that neither the farmers
nor the city have to sign a long term
contract.
BURLEY, IDAHO
Hurley is a community in south-
eastern Idaho with a population of ap-
proximately 10,000, The city has a
two cell series lagoon system, with a
36-acre primary cell and a secondary
cell of 44 acres. Phase I
to the pond are presently
eluding construction of a
gallon aeration pond (to
stabilization lagoons and
Table 3. Upgrade design factors La Grande
wastewater treatment facilities.
improvements
underway in-
million
precede the
increase sy-
stem capacity) and chlorination facili-
ties. Static tube aerators were selected
for the aeration pond over surface
aerators because: 1) Floating aerators
are difficult to operate under winter
icing conditions; 2) diffused air
systems should not lower the winter
water temperature as rapidly as floating
aerators. Since biological activity
is a function of temperature, the dif-
ference in cooling rates relates direct-
ly to effluent quality.
The Phase I improvements are not
expected to satisfy effluent require-
ments. The project was broken into two
phases while the city waited for a re-
sponse to its request for a suspended
Item
Facilities
Required
I. AERATION CELL
A. Blower Facility
Number of Units
(Now)
(Future)
Type
Capacity, Each
B. Aeration Equipment
Number of Units
Type
Av. Capacity,
Each
C. Aeration Cell
Liquid Depth (min.)
Detention Time @
Maximum Month
Flow
Detention Time,
Peak Flow
II. CHEMICAL TREATMENT
A. Flocculation Basin
Number of
Flocculators
Energy Input, G
Basin Detention
Time, Peak Flow
B. Air Flotation
Number of Units
Overflow Rate
(including recycl
@ peak flow)
Recycle Ratio,
Minimum
Air to Solids
Ratio
Operating Pressure
C. Sludge Pumps
Number of Pumps
Type
Capacity Each
in. FILTRATION
Number of Units
Type
Overflow Rate
Maximum
Backwash Rate
3
1
Centrifugal
1,250 scfm
165
Helixical
Mixing
22 cfm
11.5 feet
3 days
1.5 days
40 sec"-"-
18 Minutes
2
e
1.8 gpm/feet^
16 Percent
0.015
80 psig
Positive Dis-
placement
70 gpm
IV. SLUDGE LAGOONS
Number of Cells
Liquid Depth
Area, Each Cell
Ultimate Disposal
Method
Automatic Back-
wash (ABW)
3 gpm/ft2
20 gpm/ft2
4
2 feet
2 acres
Landfill
70
-------
solids waiver. The State of Idaho,
Department of Health and Welfare, has
recently determined that Burley must
provide secondary treatment. Because
of high system infiltration, the second-
ary treatment requirement for 85 percent
removal translates to an effluent stan-
dard of 20 mg/1 for BOD and TSS.
The Burley Facilities Plan (6) and
subsequent addendum indicated the cost
effective Phase II alternative would be
chemical addition (alum) followed by air
flotation and dual media filtration.
Even though this alternative was cost
effective, it was also recognized to be
operationally cost intensive. Recent
advances in the science of wastewater
treatment offer the potential for a
lower cost innovative treatment system
using the existing Burley lagoons and
adding both the following two com-
ponents:
1. Microstraining--recently de-
veloped polyester fabrics for micro-
strainers have reduced the effective
pore sizes to the range of 1 micron.
Algae in the Burley lagoon have been
found to range in the 4 to 5 micron
size. Microstrainers should, therefore,
be able to remove algae solids without
the addition of coagulating chemicals.
The algae removed during this process
is intended to be recycled back to the
primary pond to provide a seed to help
maintain optimum algae concentrations.
With all algae solids being recycled the
system becomes essentially a closed loop
and additional solids handling capacity
is needed.
2. Aquaculture--Raising a poly-
culture of fish species, designed speci-
fically to feed on algae, should help
minimize the algae solids buildup pro-
duced by the microstrainer. The fish
will only be present during summer
months. Since the fish should gain
about one pound for every four pounds
of algae they consume, their harvesting
should allow sufficient removal of bio-
mass from the lagojsns to maintain long
term system equilibrium.
Because the process components of
this treatment system are relatively un-
tried (especially in colder climates, as
in Burley) they must be pilot tested
prior to full scale operation.
Zurn Industries, Inc., has volun-
teered the use of a 4-foot diameter by
2-foot long microscreen to the City of
Burley for a 3 month period in the fall
of 1978. The pilot microscreen will be
operated continuously over this period to
determine: 1) The feasibility of using
microstrainers for lagoon algae removal
in both summer and winter condition; 2)
the allowable design loading rate in
gallons per minute per square foot of
screen; 3) the potential for long term
slime buildup on the surface of the
microscreen and any resulting deleterious
impacts.
The aquaculture testing will be
performed under the guidance of Profes-
sor Jack Griffith of Idaho State Univer-
sity. The pilot work he will conduct in
1978 includes toxicity and growth rate
testing of several species of fish
selected either for their ability to
directly consume algae or to stimulate
zooplankton, which feed on algae. The
treatment capability achievable with the
aquaculture system will not be deter-
mined until the full scale system is
implemented, perhaps in 1980. Fish
yields on the order of 500 pounds per
acre per year are expected.
There are several ways that aqua-
culture could complement the microscreen
operations, including: 1) Aquaculture
may allow the microscreens to produce
a better effluent than they could alone.
2) By keeping the lagoon in a solids
(algae) equilibrium, aquaculture may de-
lay the time when sludge buildup requires
that the lagoon be cleaned out. 3) On
an annual basis, aquaculture should de-
crease the algae loading to the micro-
screen. This decreased loading may pro-
long the life of the screen fabric.
4) Aquaculture•alone may be able to meet
effluent quality requirements during
summer months, resulting in power savings
from not running the microstrainer.
Aquaculture is not developed in
Idaho and, therefore, a market for the
fish must be found. There is a mink
farm near Burley that will pay $35 per
ton for fish. Much of the pilot pro-
gram and early implementation efforts
will be directed toward developing a
better market for fish. The fish are
not intended for human consumption. In-
come from the sale of fish is not ex-
pected to cover the total cost of the
aquaculture program, especially during
the first years of implementation.
DISCUSSION
Figure 5 shows the results of our
literature review and field investiga-
tions of algae solids removal techniques.
At any required effluent quality, process
selection should be based on both a cost
effective analysis and on the requirement
for maximizing the simplicity inherent
in lagoon operation. For example, both
microstraining and air flotation can meet
a 30 mg/1 TSS requirement. Cost con-
siderations aside, microstraining is a
71
-------
superior choice because microstrainers
are operated by simple hydraulic con-
siderations and do not require chemical
handling.
All alternatives must be evaluated
on their potential for implementation
as well as their technical and cost
effective merits. For example, select-
ing a land disposal alternative will be
fruitless if it will be next to im-
possible to acquire the necessary land.
Regulatory agencies can impose schedul-
ing deadlines which don't allow the time
necessary to obtain complicated pipe-
line rights-of-way, form irrigation
districts, or develop long term land
lease agreements. These institutional
considerations, must be considered during
alternative selection.
In conclusion, wastewater lagoons
provide stable, reliable treatment that
unfortunately doesn't quite meet second-
ary standards. Increasingly, methods
are becoming available to upgrade lagoon
effluent quality and still retain the
numerous advantages offered by stabiliza-
tion ponds.
ACKNOWLEDGMENTS
I would like to thank the following
individuals for their sincere coopera-
tion in completion of this paper: Mr.
Doug Tietze, Public Works Director for
Ontario, Oregon; Mr. William A. Hamil-
ton, P.E., City Engineer for La Grande,
Oregon; and Mr. Bob Martin, City Water
and Sewer Superintendent for Burley,
Idaho.
BIBLIOGRAPHY
!• Rhett, John T.,- "Wastewater Treat-
ment Ponds/Secondary Treatment,"
United States Environmental Protec-
tion Agency, memo, April 29, 1975.
Removal Technique
References
Effluent TSS Potential, mg/1
Stabilization Pond
Alone
Phase Isolation
Air Flotation with
Alum Addition
Microstrainer and
Aquaculture*
Intermittent Sand**
Filtration
Air Flotation & Filtration
with Alum Addition
Land Application
(3) (5)
(4)
(6)
(2) (7) (8) (9)
(10) (11) (12)
(13) (14) (15)
(8) (16) (17)
(18) (19)
(8) (20) (21)
(22) (23) (24)
(2) (7) (9) (10)
(11) (15)
(25) (26) (27) (28)
70
60 50
40
30 20
10
•Effluent quality to be determined by pilot testing in Fall 1978. Estimate based on
data supplied by ENVIREX.
**Effluent quality based in part on interview with plant operator and site visit at
Mt. Shasta, California in March 1977.
Figure 5. Algae removal techniques.
72
-------
10.
11.
12.
13.
Summary Report 'Apollo County
Park1 Wastewater Reclamation Project
for Antelope Valley Area," Depart-
ment of County Engineers, County of
Los Angeles, California, October
1971.
"Wastewater Facilities
of Ontario, Oregon,"
CH2M HILL,
Plan, City of „..„„....„
Boise, Idaho, April 1975
Hiatt, A. L., "'Phase Isolation'
Concept Meets Discharge Require-
ments," Public Works, page 70,
December 1975.
CH2M HILL, "Wastewater Facilities
Plan, City of La Grande, Oregon,"
Boise, Idaho, September 1975.
CH2M HILL, "Wastewater Facilities
Plan, City of Burley, Idaho,"
Boise, Idaho, May 1977.
Dryden, F. D. and G.Stern, "Reno-
vated Wastewater Creates Recrea-
tional Lake," Environmental Science
and Technology, 2, 4, 268, April
1968.
Middlebrooks, et al., "Evaluation
of Techniques for Algae Removal
from Wastewater Stabilization
Ponds," Utah Water Research Labora-
tory, PRJEW115-1, Logan, Utah,
January 1974.
CH2M HILL, "Feasibility Study,
Advanced Treatment of Polishing
Pond Effluent, Forest Grove Waste-
water Treatment Plant," Unified
Sewerage Agency, Washington County,
Oregon, April 1973.
Parker, D. S. et al., "Improving
Pond Effluent by Algal Removal,"
Brown and Caldwell, San Francisco,
California, 1972.
Mees, Q. M., C. E. Parker, and E. S.
Geiser, "Reclamation of Lagoon
Effluent," Paper presented at
Arizona Water Pollution Control
Association, 26, 1, 1966.
Stewart, M. J. "Chemical Treatment
of Stabilization Pond Effluent
Followed by High Rate Classifica-
tion," presented at the 40th annual
meeting of the Pacific Northwest
Pollution Control Association,
Vancouver, British Columbia, October
1973.
Friedman, A. A. et al., "Algae
Separation from Oxidation Pond
Effluents," presented at 30 Annual
Purdue Industrial Waste Conference,
West Lafayette, Indiana, May 1975.
14.
15,
16.
17,
18.
19.
20.
21.
22.
23.
McGarry, Michael G., "Algae Floc-
culation with Aluminum Sulfate and
Polyelectolytes,» Journal of the
Water Pollution Control Federation,
42, page R2191, May 1970.
Caldwell, D. H. et al., "Upgrading
Lagoons," prepared for EPA Tech-
nology Transfer Seminar by Brown and
Caldwell, Consulting Engineers,
Walnut Creek, California, June
1977.
Brown and Caldwell, Cons. Eng.
"Supplement to Upgrading Lagoons,"
prepared for the EPA Technology
Transfer Design Seminar for Waste-
water Treatment Facilities, Boise,
Idaho, November 1974.
Griffith, J. S., "A Wastewater
Aquaculture System for the City of
Burley, Idaho," A preliminary
research proposal submitted to Idaho
State Department of Health and
Welfare, June 1978.
Jokela, A. T .
n-- n --3 t ion
u u ft e? J. d , ri. i • auu ft • "», Hcaueri
Reclamation, Aquaculture, and
Wetland Management," A paper pre-
sented at Coastal Zone 78, Symposium
on Technical, Environmental, Socio
Economic, and Regulatory Aspects of
Coastal Zone Planning and Manage-
ment, ASCE, San Francisco, Califor-
nia, March 14, 1978.
Wert and Henderson, "Feed Fish
Effluent and Reel in Savings," Water
and Waste Engineering, page 38, June
1978.
Marshall,G. R. and E. J. Middle-
brooks, "Intermittent Sand Filtra-
tion to Upgrade Existing Wastewater
Treatment Facilities," Utah Water
Research Laboratory, PRJEW 115-2,
Logan, Utah, February 1974.
Middlebrooks and Marshall, "Stabili-
zation Pond Upgrading with Inter-
mittent Sand Filters," Utah State
University, Logan, Utah, 1974.
Middlebrooks, et al., "Intermittent
Sand Filtration to Upgrade Lagoon
Effluents — Preliminary Report,"
Utah State University, Logan, Utah,
August 1974.
Middlebrooks, et al., "Single and
Multi-Stage Intermittent Sand
Filtration to Upgrade Lagoon Ef-
fluents, A Preliminary Report," A
paper presented at EPA Technology
Transfer Seminar on Wastewater
Lagoons, Boise, Idaho, Novem-
ber 1974.
73
-------
24. Reynolds, J. H., et al., "Intermit-
tent Sand Filtration to Upgrade
Lagoon Effluents," A paper pre-
sented at Symposium on Performance
and Upgrading Wastewater Stabiliza-
tion Ponds, Utah State University,
August 23, 1978.
25. Chaiken, B. I., S. Poloncsik, and
C. D. Wilson, "Muskegon Sprays
Sewage Effluent on Land," Civil
Engineering, ASCE, 43, 5, 49, May
1973.
26. CH2M HILL, "Conceptual Design of
Land Disposal of Primary Effluent,"
Taterstate Frozen Foods,
Washburn, Maine, March 1975.
Inc ,
27. CH2M HILL, "Ground-Water Investiga-
tion of the Land Treatment Site,"
Taterstate Frozen Foods, Inc.,
Washburn, Maine, July 1975.
28. Wallace, A. T., "Land Application
of Lagoon Effluents," A paper
presented at Symposium on Perfor-
mance and Upgrading Wastewater
Stabilization Ponds, Utah State
University, August 23, 1978.
74
-------
FIELD EVALUATION OF ROCK FILTERS FOR REMOVAL
OF ALGAE FROM LAGOON EFFLUENTS
Kenneth J. Williamson and Gregory R. Swanson*
INTRODUCTION
Aerobic stabilization lagoons are
most commonly employed by small munici-
palities and isolated industrial plants
for wastewater treatment. Their popular-
ity in these applications is due to
relatively low construction costs and
high reliability, and especially due to
minimal operation and maintenance re-
quirements. A major limitation of
lagoons, however, is the presence of
occasionally large quantities of algae in
the effluent.
The Clean Water Act of 1972 (Public
Law 92-500) required that all municipal
effluents meet secondary treatment
standards, defined by the EPA as a
maximum of 30 mg/1 of both 5-day bio-
chemical oxygen demand (BOD^) and total
suspended solids (TSS) on a monthly
average basis. Compilation of data on
lagoon treatment throughout the U.S.,
however, soon revealed that most lagoons
could not meet a 30 mg/1 TSS standard
year-round because of the algal content
of their efflue.nts.
Consequently, a significant research
effort was directed at finding effective
methods for upgrading lagoon effluents,
especially through the removal of algae.
Middlebrooks et al. (1) summarized the
results of this research effort and
compiled a list of 14 possible tech-
niques.
1. Centrifugation
2. Microstraining
3. Coagulation-
Flocculation
4. In-pond removal of particulate
matter
5. Complete containment
6. Biological disks, baffles, and
raceways
*Kenneth J. Williamson is Associate
Professor of Civil Engineering, and
Gregory R. Swanson is Graduate Research
Assistant, Oregon State University,
Corvallis, Oregon.
7. In-pond chemical precipitation of
suspended materials
8. Autoflocculation
9. Biological harvesting
10. Oxidation ditches
11. Soil mantle disposal
12. Dissolved air flotation
13. Granular media filtration
14- Intermittent sand filtration
In evaluating these processes, emphasis
was appropriately placed on the criteria
of ease of operation, minimum maintenance
and cost, and dependability of operation.
Only microstraining, soil mantle dis-
posal, granular media filtration and
intermittent sand filtration were con-
sidered promising based on these criteria.
An additional, promising alternative
for the removal of algae from lagoon
effluents is the rock filter. Very
simply, a rock filter consists of a
submerged bed of rocks (5 to 20 cm
diameter) through which the lagoon
effluent is passed vertically or hori-
zontally, allowing the algae to become
attached to the rock surface and thereby
be removed. The basic simplicity
of operation and maintenance are the key
advantages of this process. The effluent
quality achievable and the dependability
of long-term operation, however, have not
yet been proven.
Beginning in 1970, initial research
into the rock filter was undertaken at
the University of Kansas (2-6) from which
O'Brien (16) concluded that:
1. Peak efficiency for submerged
rock filters is achieved during the
summer and early fall: this efficiency
can produce an effluent meeting 30
mg/1 BOD5-30 mg/1 total suspended
solids discharge standards. During the
winter and spring the efficiency of
suspended solids removal decreases
significantly.
2. The filters may be anaerobic
during the summer and early fall and will
produce hydrogen sulfide if sulfates are
present.
75
-------
3- The rate of solids accumulation
in submerged rock filters should allow an
effective filter life of greater than 20
years.
4. Rock sizes should be greater
than 2.54 cm and less than 12.70 cm.
O'Brien did not elaborate on the
basic mechanism of algal removal in
rock filters, nor the possible effluent
quality which could be achieved at
lower loading rates than those used of
0.40-2.67 m3/m3-day (3-20 gpd/ft3).
Recently the EPA has promulgated
regulations allowing variances from
the secondary treatment TSS limitation of
30 mg/1 for municipalities which employ
lagoons due to the lack of an appropriate
technology to upgrade lagoon effluents.
Nevertheless, emphasis on improving
effluent water quality necessitates
development of dependable lagoon effluent
polishing techniques.
The Veneta Rock Filter
A full-scale rock filter was de-
signed and constructed as part of a
lagoon expansion and upgrading project at
Veneta, Oregon, in 1975. The regional
EPA was in full support of this project
and contracted with the writers to
provide a field evaluation of the rock
filter system.
A schematic flow diagram of the
Veneta, Oregon, wastewater treatment
system is shown in Figure 1. The system
treats wastewater from a population
of approximately 2200 with no industrial
wastewater contribution. Raw wastewater
is pumped into the larger first cell and
flows through the smaller second cell by
gravity. Both lagoons are designed for a
minimum water elevation of 0.76 m (2.5
ft) and a maximum of 1.83 m (6.0 ft).
Lagoon effluent is then pumped to the
rock filter by a submersible pump with a
maximum capacity of approximately 25 1/s
(400 gpm).
A plan and cross-section of the rock
filter is shown in Figure 2 The
pressure pipe carrying lagoon effluent
discharges into a 0.3 m (1.0 ft) square
influent channel upon entering the rock
filter. The influent channel is covered
with trench grating which improves the
distribution of flow. The lagoon ef-
fluent rises from the influent channel
and moves horizontally towards the
discharge weirs where it flows into a
covered effluent channel. Finally, the
flow from each side of the rock filter is
combined, chlorinated, and discharged to
the nearby Long Tom River. The rock
surface is approximately 0.30 m (1.0 ft)
above the water elevation to prevent
growth of algae on the rock filter.
The effective surface area of the
rock filter is 5400 m2 (58,000 ft2)
and the effective volume is 8,200 rrP
(290,000 ft3). The in situ averge
porosity of the 7.6 - 15.2 cm (3 - 6 in)
rock bed was measured as 42 percent.
REMOVAL MECHANISM
Sedimentation is probably the
primary entrapment mechanism in the
rock filter due to the large pore sizes.
This hypothesis is supported by the
observation that algal residues are
primarily found on the top of rocks in
the Veneta rock filter. As a result, the
settling rate of algae is probably
the basic physical parameter controlling
the efficiency of algae removal.
Measurement of Algal
Settling Rates
Algae are typically assumed to
settle as individual, non-flocculating
particles; this process is classified as
discrete settling. Discrete settling is
assumed for lakes and ponds (7) and this
assumption is extended to include rock
filters.
The settling rates of algal cultures
can be measured in a settling chamber
under quiescent conditions (8, 9, 10). A
fluorometer is used to measure the
fluorescence of the algal cells as they
settle past an optical window. The main
advantages of this method are high
sensitivity and simplicity. Assumptions
and techniques used are described in
detail by Stutz and Williamson (9).
Stutz and Williamson (9) found that
the variables of temperature and algal
species influenced settling rates sig-
nificantly. Settling rates were not
sensitive to either aerobic or anaerobic
dark incubation; these would be the
conditions found in the rock filter.
Algal settling curves will typically
have the shape shown in Figure 3a;
an actual curve for a sample from the
Veneta lagoon is shown in Figure 3b.
This curve represents the recorder traces
from the fluorometer output during
the settling test and is specific for the
fixed settling depth of the settling
chamber (usually 10 mm). The exact shape
of the curve is determined by the size
distribution of the algal culture (8).
The characteristic linear portion of
the curve is used to define the mean
76
-------
settling velocity which is calculated
as:
MSV
where:
MSV
S
D
S.D/100 ...... (1)
mean settling velocity
initial slope from Figure 3a
settling depth in settling
chamber
The mean settling velocity can be used to
compare settling rates under different
environmental conditions and for dif-
ferent species (9) and to model algal
dynamics in natural waters (7).
In describing settling in a rock
filter, however, the nonlinear portion
of Figure 3a is more important than the
linear portion since predictions of
removals greater than 50 percent are
required. By assuming that the algal
mass is proportional to fluorescence, the
curve in Figure 3a can be transformed
into the curves in Figure 4a as:
R = 100 - RF
(2)
RAW
WASTEWATER
^, WET
"'"IWELL
LAGOON
CELL NO. I
4.51 ha
( 11.14 acres)
LAGOON
CELL NO. 2
1.47 ha
(3.63 acres)
LAGOON
EFFLUENT
SAMPLES
ROCK
Fl LTER
0.57 ha
(1.40 acres)
ROCK FILTER
EFFLUENT
SAMPLES
DISCHARGE
TO LONG
TOM RIVER
Figure 1. Schematic flow diagram of the wastewater treatment system at Veneta,
Oregon.
77
-------
where:
R =
RF =
percent removal
relative fluorescence in settling
test
The characteristic shape of Figure 3a
gives a straight line portion in Figure
4a over a range of R from about 60 to 100
percent. This is the portion of the
curve which is applicable to the design
of rock filters. The transformation of
the settling test data in Figure 3b is
shown in Figure 4b; a linear response for
R down to 15 percent was observed.
Figure 4 cannot be directly applied
to the design of a rock filter be-
cause the effective settling depth in the
rock filter is not equal to the settling
depth in the settling chamber. The
effective settling depth in the rock
filter depends directly on the pore sizes
which will be determined by the size and
gradation of rocks. Studies are pre-
sently being conducted to estimate a
settling depth for the Veneta rock
filter.
It can be concluded from Figure 4
that algal sedimentation in the rock
filter should be a linear function of
1/0. The proportionality coefficient
is unknown. This r e-lationship should
hold for TSS, chlorophyll, and particu-
late BOD removal.
EFFLUENT
INFLUENT
EFFLUENT
EFFLUENT
/
V
X
v
V
*•*"
1
36.9 m
^7.3 m
INFLUENT
PIPE
:.
. 36.9m
7.3m
7.3m--
52.4m
J
7.3m
r— •*
Sj
;
y
\
)
EFFLUENT
WEIR
7.3m
PLAN
73.8m
7.3m
INFLUENT PIPE
PROFILE
Figure 2. Rock filter located at Veneta, Oregon.
78
-------
SAMPLING AND
ANALYTICAL METHODS
Samples were collected and analyzed
for 7 consecutive days out of each
month. This schedule was chosen to
provide data on both long-term and
day-to-day performance without over-
extending available resources. Samples
were collected from the rock filter
influent (lagoon effluent) and the rock
filter effluent as shown in Figure 1.
Rock filter effluent samples were col-
lected prior to chlorination so that
interferences from chlorine would be
eliminated in subsequent analysis.
A portable automatic sampler (ISCO
model 1580) was installed at each
sample point to collect 24-hour composite
samples. The sample bottle in each
sampler was packed in ice to bring sample
temperature to 4oc or below. Com-
posite samples were transferred to
1-liter plastic bottles and transported
to the Corvallis laboratory for analysis
of major wastewater constituents
Additionally, grab samples were collected
for analysis of constituents whose
concentration could be affected by
automatic sampling or by storage for 24
hours. Grab samples were generally taken
in the mid-afternoon. Temperature,
dissolved oxygen, pH and sulfide analyses
were performed on-site using grab
samples.
Analysis of other constituents,
including ammonia nitrate, suspended
solids (total and volatile), organic
nitrogen, phosphorus, chlorophyll,
BODc, COD, and TOC were performed on
24-hour composite samples. Composite
samples were preserved by refrigeration
at 0°C and the addition of 0.8 ml
per liter.
A summary of parameters analyzed,
sample storage and analysis methods,
and equipment used is given in Table
1 .
100
UJ 7 =
(J '3
z
50
O '
UJ
O
-------
Table 1. Summary of analytical techniques.
Parameter
Type of Sample
Sample Storage
and/or Preservation
Method of Analysis
Equipment Used
Reference
00
o
Temperature
DO
NH4
N0~ > 1 mg/1
< 1 mg/1
TSS & VSS
Organic N
Phosphorus (total
and soluble)
Chlorophyll
COD
TOC
Grab
Grab
Grab
Grab
24-hour composite
24-hour composite
24-hour composite
24-hour composite
24-hour composite
24-hour composite
24-hour composite
24-hour composite
On-site
On-site
On-site
On-site
24-hour composite On-site
24-hour composite On-site
Thermistor
Membrane electrode
Electronic pH meter
Ion-specific electrode
Ion specific electrode
Known addition method
Ion specific electrode
Known additional method
Refrigeration @ 0 C Brucine method
+ 0.8 ml H2S04/1
On-site filtration Gravimetric
Refrigeration at 0°C
On-site filtration
Refrigeration @ 0°C
+ 0.8 ml H2S04/1
Immediate filtration
Kjeldahl digestion
Acidimetric finish
Digestion with l^SO^ &
HNO.J. Vanadomolybdophos-
phoric acid method
Spectrophotometric
Immediate preparation BOD bottle
Refrigeration at 0°C Dichromate digestion
+ 0.8 ml H2S04/1
Refrigeration at 0°C TOC analyzer
+ 0.8 ml H2S04/1
YSI thermistor &
YSI model 54 elec-
tronic meter
YSI DO probe & YSI
model 54 electronic
meter
Coleman Model 37A pH
meter. Coleman glass
& calomel electrodes
Orion model 94-16A
sulfide probe & model
407 specific ion meter
Orion model 95-10
NH3 probe & Orion
model 407 meter
Orion model 92-07
NOJ probe model 407
specific ion meter
Spectronic 20 spectro-
photometer
GF/C
Filter paper & Mettler
Type HIS balance
Std. Kjeldahl apparatus
Micro-Kjeldahl digestion
apparatus. Beckman model
DB spectrophotometer
Heath Model EU-700
spectrophotometer
300 ml BOD bottles
YSI model - DO probe
Std. COD digestion
apparatus
Oceanography Intl.
Model 0524B TOC analyzer
Standard Methods,
p. 450 (11)
Standard Methods,
p. 460
Orion Research (12)
Standard Methods,
p. 381
Orion Research (14)
Yu S, Berthouex (13)
Standard Methods,
p. 94, 96
Standard Methods,
p. 437
Standard Methods,
p. 466
Standard Methods,
p. 1029
Standard Methods,
p. 543
Standard Methods,
p. 550
Oceanography Intl.Qjj
Standard Methods,
p. 532
-------
RESULTS
Operational History
The City of
meet secondary
from November 1
allowed to discharge
dry weather period
October 31). Each spring
is drawn down to 0.76 m (2.5
for storage of all flows
Veneta is required to
treatment standards
to May 31 and is not
during the summer
(June 1 through
the lagoon
ft) to allow
during the
dry weather period. The rock filter is
drained after discontinuance of dis-
charge and left dry until the fall.
Discharge during the fall 1977 was
begun on 11/10/77. The rock filter
was filled with lagoon effluent and
drained twice prior to startup. The
sampling schedule used is shown in Figure
5.
Flooding of the adjacent Long Tom
River during December 1977 restricted
the discharge and resulted in ponding of
the rock filter to about 0.3 m (1
ft) above the rock surface elevation. As
a result, discharge and sampling were
discontinued. Discharge was renewed in
late December and sampling was begun on
1/1/78. The discharge rate was set at
the maximum pumping capacity ( -v 400 gpm)
due to the extremely high lagoon levels
(> 2 m) and maintained at that rate
through March.
Beginning in the February sampling
period, a sulfide odor was apparent
in the vicinity of the effluent manhole.
However, sulfides could not be mea-
sured above the minimum detectable
concentration of the sulfide probe
(0.1 mg/1) . The sulfide odor was re-
duced, but still noticeable in March,
April, and May.
By mid-March, the high effluent
pumping rate finally began to reduce
the lagoon level. By 4/10/78, the lagoon
was drawn down to the minimum water
level of 0.76 m (2.5 ft) and discharge
was discontinued. Discharge was re-
newed on 4/13/78 a.t ^ 100 gpm and
increased to >b 200 gpm on 4/17/78
during the April sampling period.
In the May sampling period, the
lagoon level was at 0.9 m (3.0 ft)
and an algal bloom was in progress.
1 20
IOO
60
• INFLUENT TSS
• INFLUENT BOD5
D EFFLUENT TSS
<^_ O EFFLUENT BOD5
50 h-
E
— 40
CO
CO
Q
O
m
30
20
IP
••
..
on
o
""
-.:•
° 0°
0
00 0
1 1
I3I4I5I6I7I8I9 1234567 5 6 7 8 9 1011 56789IOII 16 17 18 19202122 14 B 16 17 18 1920 3031 1 2 3 4 5
7 5/78 7-8/78
H/77
1/78
2/78
3/78
4/78
Figure 5. Influent and effluent BOD5 and TSS over study period.
81
-------
Lagoon effluent suspended solids were
33 mg/1 at the beginning of the week and
rose to 61 mg/1 by the end of the week.
A variance of the city's discharge
permit was requested of the Oregon
Department of Environmental Quality (DEQ)
to allow discharge during the sum-
mer dry weather period. This request was
made so that data on summer opera-
tion of the rock filter could be ob-
tained This request was granted by
the DEQ based on the following, more
stringent, effluent limitations:
Parameter
Monthly
Average
10 mg/1
10 mg/1
WeekJLy
Average Average
15 mg/1 20 mg/1
15 mg/1 20 mg/1
BOD
TSS
Fecal
Coliform 200/100 ml 400/100 ml
pH within the range of 6.0 to 9 0
Effluent BOD concentration in mg/1
divided by the dilution factor
(ratio of receiving stream flow to
effluent flow) shall not exceed
1 .
Due to the low lagoon level and the
high evaporative rate during the summer,
however, discharge was not begun until
7/21/78 when the lagoon level reached 1.2
m (4.0 ft). By this time, a bloom of
blue-green algae had caused the lagoon
effluent TSS to exceed 100 mg/1.
Data and Data Analysis
Daily rock filter influent and
effluent BOD5 and TSS values over
the seven sampling periods completed to
date are shown in Figure 5. Good sus-
pended solids removals (> 70 percent)
were obtained beginning with the first
sampling on 11/13/77, 3 days after the
fall startup. This supports the theory
that the removal mechanism is primarily
physical (settling) and not biological.
Percentage removals of suspended
solids were lower during the winter
months of January, February, and March
due to the high effluent pumping rate,
Table 2. Data summary for rock filter.
Weekly Averages
Parameter
r-
n
0
CNl
-~- O
rH 4-1
-^ O rH
in -u i—i
O
4J
vO O CM
rH 4-1 CM
0 0
4J CM
O O ^
m -u m
Hydraulic
Loading
(I/days)
Temperature
rH rH
r-t i— 1
Ia Ea
0.13
8.4 8.6
i— i i— i
I E
0.28
6.0 6.3
CM OJ CO CO
I E I E
0.28 0.27
9.3 9.0 10. 6 9.8
-------
but the lower algal concentrations in the
lagoon effluent during these months
resulted in final effluent BODc and TSS
values of less than 20 mg/1 on all
days sampled.
The rock filter effluent TSS did not
exceed 15 mg/1 and the BODc did not
exceed 20 mg/1 over the study period,
except on 4/17/78, when a BOD5 of
29 mg/1 was recorded. This value was
much higher than all other BOD^ values
reported that week, however, and may have
been an analytical error. The low lagoon
levels during the spring resulted in
increased soluble BOD^ values that were
not removed in the rock filter. As a
result, higher effluent
were noted.
BOD5 values
A summary of all rock filter in-
fluent and effluent data completed
to date is shown in Table 2. These data
are averages of the 7 consecutive
days of sampling during each sampling
period. The hydraulic loading indicated
was the pumped flow rate divided by the
total rock filter volume (m3 water/m3
rock filter-day or 1/days) Water
temperature increased slightly in passing
through the rock filter during the winter
months, but decreased during the summer.
The pH of the lagoon effluent approached
10 during summer periods of heavy
photosynthesis, but the rock filter
provided sufficient detention time
without photosynthetic activity so that
dissolved carbon dioxide was replenished
and the pK lowered to between 7 and
As mentioned previously, dissolved
oxygen (DO) readings were taken on grab
samples, generally in the mid-afternoon.
Therefore, the influent (lagoon effluent)
DO values do not. represent the diurnal
variations in DO which occur in lagoons.
The rock filter undoubtedly dampens these
diurnal variations to a large extent;
therefore, the effluent DO values shown
are probably representative of average
conditions.
Ammonia-nitrogen was observed to
increase noticeably in passing through
the rock filter during the warmer months
(Figure 6). This is apparently the
result of increased biological degrada-
tion rates at these times. Due to
the existence of both aerobic and anoxic
25
820
15
1 (0
O
z
*«
O
2 10
<
O
cr
o
.. 5
I
NOj-N
| Org -N
I = INFLUENT
E = EFFLUENT
I E
11/77
I E
1/78
IE IE IE IE
2/78 3/78 4/78 5/78
SAMPLE DATE
Figure 6. Weekly averages of NH4+-N, Org-N and N03" for rock filter.
83
-------
zones in the rock filter at most times,
both nitrification and denitrification
are possible, even simultaneously. A
small amount of nitrification appeared to
occur during the colder months, changing
to an apparent predominance of denitri-
fication in the summer. The amount of
biological nitrification and denitrifica-
tion which can be supported in a rock
filter, however, is definitely limited;
nitrification by the limited oxygen
content in the influent stream and
denitrification by variations in the
extent of the anoxic zone.
Chlorophyll concentrations are
indicative of viable algae and removal
can be directly correlated with suspended
solids removal as shown in Figure
7. Variations in the proportion of
chlorophylls a, b, and c between sampling
periods are indicative of changes in
dominant algal species. Additionally,
beginning in March 1978, grab samples
were analyzed once each sampling period
for algal species and counts. Results of
this analysis are contained in Appendix
A.
Correlation with Settling Theory
For discretely settling particles,
the percentage removal of suspended
solids should be a direct function of
hydraulic loading rate. This appears
to be the case for the removal of sus-
pended solids in the rock filter as
shown in Figure 8. This relationship is
100
80
LU
cc.
I
Q_
60
40
cr
o
_i
O 20
• CHLOROPHYLL a
A CHLOROPHYLL b
• CHLOROPHYLL
-------
100
80
o
2
UJ
CO
CO
60
40
20
I
I
O.I 0.2 0.3
HYDRAULIC LOADING RATE ( I/days)
Figure 8. Total suspended solids removal versus hydraulic loading rate.
o>
E
co
CO
Q
O
CD
25
20
15
10
r
• TSS
A BODC
1
O.I 0.2 0.3
HYDRAULIC LOADING RATE (I/days)
0.4
0.4
Figure 9. Effluent quality from rock filter as a function of hydraulic flow rate.
85
-------
20 40 60 80
TSS REMOVAL (mg/l)
100 8,
Figure 10. Correlation of BODc removal n
to TSS removal.
4. BOD removal in the rock filter
primarily results from settling of
particulate BOD with little net removal
or generation of soluble BOD.
5. Rook filters appear to be
compatible with the capabilities of
typical lagoon operators.
REFERENCES
1. Middlebrooks, E. J., D. B. Porcella,
R. A. Gearheart, G. R. Marshall,
J. H. Reynolds, and W. J. Grenney.
Techniques for Algae Removal from
Wastewater Stabilization Ponds. J.
Water Pollution Control Fed., 46,
2676 (1974).
2. Martin, D. M. Several Methods
of Algae Removal in Municipal
Oxidation Ponds. M S. Thesis,
University of Kansas, Lawrence
(1970).
3. O'Brien, W. J., R. E. McKinney,
M. D. Turvey, and D. M. Martin. Two
Methods for Algae Removal from
Oxidation Pond Effluents. Water and
Sewage Works, 120, No 3, 66 (1973).
Martin, J. L. and R. Weller. Re-
moval of Algae from Oxidation Pond
Effluent by Upflow Rock Filtration.
M.S. Thesis, University of Kansas,
Lawrence (1973).
10,
11.
12.
13.
14,
15.
16,
O'Brien, W. J. Polishing Lagoon
Effluents with Submerged Rock
Filters, Upgrading Wastewater
Stabilization Ponds to Meet New
Discharge Standards. Report
PRWG 159-1, Utah Water Research
Laboratory, Utah State University,
Logan (1974).
Hirsekorn, R. A. A Field Study
of Rock Filtration for Algae Removal.
M.S. Thesis, University of Kansas,
Lawrence (1974) .
Bella, D. A. Simulating the
Effect of Sinking and Vertical
Mixing on Algal Population Dynamics.
J. Water Pollution Control Fed., 42,
5, Part 2, R 140 (1970).
Titman, D. A Fluorometric Technique
for Measuring Sinking Rates of
Freshwater Phytoplankton. Limn, and
Ocean., 20, 869 (1975).
Stutz-McDonald, S. E., and K. J.
Williamson. Settling Rates of Algae
from Wastewater Lagoon. Paper
submitted to the J. Environmental
Engineering Div., ASCE.
Eppley, R. W., R. W. Holmes, J.
D. H. Strickland. Sinking Rates of
Marine Phytoplankton Measured with a
Fluorometer. J. Exp. Mar. Biol.
Ecol., 1, n91 (1967).
Standard Methods for the Ezao-
inavion of Water and Wastewater.
(14th ed.) American Public Health
Association, New York, NY, 1975.
Applications Bulletin No. 12:
Determination of Total Sulfide
Content in Water. Orion Research,
Inc., Cambridge, MA (1969).
Yu, K. Y., and P. M. Berthouex.
Evaluation of a Nitrate-Specific Ion
Electrode. J. Water Pollution
Control Fed., 49, 1896 (1977).
Instruction Manual: Nitrate Ion
Electrode Model 92-07. Orion
Research, Inc., Cambridge, MA
(1970).
The Total Carbon System: Operating
Procedures, Model 0524B. Oceano-
graphy International Corporation,
College Station, TX.
O'Brien, W. J., Algae Removal
by Rock Filtration." Trans. 25th
Annual Conference on Sanitary
Engineering, University of Kansas,
Lawrence, 1975.
86
-------
APPENDIX A
Table 3. Algal speciation for grab samples--March 9, 1978.
Rock Filter Influent
Rock Filter Effluent
Taxon
genus-species
Chlorophyta Scenedesmus acumlnatus
Chlorella vulgaris
Pyraminonas cf.
tetrarhynchus
Ankistrodesmus Falcatus
Rel.
Abundance
0.195
0.189
0.166
0.122
Chlamydomonas cf, globosa 0.047
Coccomonas sp. 0.030
Scenedesmus quadricauda 0.006
Actinastrum hantzschii 0.006
genus-species
Scenedesmus acuminatus
Chlorella vulgaris
Rel.
Abundance
0.139
0.458
Ankistrodesmus Falcatus 0.125
Chlamydomonas cf. globosa 0.028
Actinastrum hantzschii 0.014
Cyanophyta
Euglenophyta
Schizothrix calcicola
Astrasia sp.
Euglena~sp. 1
Euglena sp. 2
Trachelomonas volvocina
Pyrrhophyta Glenodinlum sp.
0.018
0.106
0.059
0.024
0.012
0.030
Euglena sp. 1 0.042
Trachelomonas volvocina 0.180
Trachelomonas sp.I0.014
Table 4, Algal speciation for grab samples--April 20, 1978.
Rock Filter Influent
Rock Filter Effluent
Taxon genus-species
Chlorophyta Chiamydomona s cf. globosa
Scenedesmus acuminatus
Euglenophyta
Rel.
Abundance
0.99
0.01
genus-species
Rel.
Abundance
Chlamydomonas cf. globosa 0.44
Scenedesmus acuminatus 0.11
0.11
0.06
Chlorella vulgaris
Actinastrum hantzschii
Euglena sp. 1 0.17
Trachelomonas sp. 1 0.11
Table 5. Algal speciation for grab samples—May 18, 1978.
Rock Filter Influent
Rock Filter Effluent
Taxon
Chlorophyta
Chrysophyta
Pyrrhophyta
Rel. Rel.
genus-species Abundance genus-species Abundance
Tetraedron regulare
Chlorella vulgaris
Scenedesmus acuminatus
Scenedesmus quadricauda
Ankistrodesmus Falcatus
Nitzschia sp.
0.75
0.05
0.12
0.04
0.01
0.02
Tetraedron regulare
Scenedesmus acuminatus
Ankistrodesmus Falcatis
Gilenodinium sp.
0.83
0.07
0.07
0.02
Table 6. Algal speciation for grab samples—August 2, 1978.
Rock Filter Influent
Rock Filter Effluent
Taxon
Cyanophyta
genus-species
Anacystis cyanea
Rel.
Abundance
(Microcystis Flos-aquae)
1.00
genus-species
Anacystis cyanea
Schizothrix calcicola
Rel.
Abundance
0.999
0.001
87
-------
COMMENT ON FIELD EVALUATION OF ROCK FILTERS FOR
REMOVAL OF ALGAE FROM LAGOON EFFLUENTS
M. L. Cleave*
Williamson and Swanson (1978) assume
that discrete settling is responsible for
removal of algal particles from lagoon
effluents. The authors use chlorophyll
extractions and relative fluorescence (an
estimate of chlorophyll) as a measure of
the efficiency of treatment by the rock
filter. Although discrete settling of
algae is assumed for lakes and ponds
(Bella, 1970), the validity of this
assumption for rock filter settling of
the Veneta lagoon effluent is question-
able because of the type of algae and the
biomass measurement technique.
The type of algae contained in the
Veneta lagoon effluent was identified
via a relative abundance index on algal
speciation conducted on grab samples
from the lagoon effluent. The algal
speciation listing of the lagoon effluent
on March 9, 1978. states that 17 percent
of the algae present were motile.
Motility would render these algae unsus-
ceptible to sinking. Also, 10 percent of
the algae, represented by the genus
Astasia, contained no chlorophyll. The
absence of chlorophyll would render this
alga unmeasurable by either fluorescence
or chlorophyll biomass indicators. The
algal speciation listing of the lagoon
effluent for April 20, 1978, states that
99 percent of the algae present were
motile. This assumes that the Chlatny-
domonas sp. listed was not in a palmel-
loid form since this was not noted as
such. The algal speciation listing of
the lagoon effluent for August 2, 1978,
states that the alga of the lagoon
effluent was 100 percent Mlcr^cy sjtj^
flos-aquae (Microcystis aeruginosa Kuetz;
emend. Elenkin 1924). This blue-green
alga contains gas vacuoles which allow it
to float to the surface of water in-
dependent of turbulence (Fogg et al.,
1973).
*M. L. Cleave is a graduate student,
Utah State University, Logan, Utah.
It was shown by Titman and Kilham
(1976) that in general, when comparing
different algal species in the same
physiological condition, the larger
algal species display a tendency to sink
more rapidly than the smaller algal
species. Many previous investigators have
shown that algal sinking rates are
not a species specific constant because
nutrient depleted cells sink 2 to M
times more rapidly than nutrient enriched
cells (Smayda, 1970, 1974; Smayda
and Boleyn, 1965, 1966; Boleyn, 1972;
Eppley et al., 1967). Therefore,
settling rates of algae should be sensi-
tive to either aerobic or anaerobic
dark incubation among other nutri-
ent/chemical variations.
The design of the rock filter is
based on algal settling tests where
Newton's law would be expected to apply.
Assuming that either Newton's or Stokes'
law applies, the settling rates of algae
are temperature dependent by definition.
Also, the algal suspension is placed in a
fluorometer and exposed to intense light
for prolonged periods of time during the
settling tests. Thus, the settling
curves could be artifacts of either
chloroplast reorientation for the eucary-
otic algae or gas vacuole degradation in
the blue-green (procaryotic) algae.
Kiefer (1973) discussed the two com-
ponents of fluorescent decay due to
movement and redistribution of chloro-
plasts within eucaryotic algal cells as
shown in Figure 1. This curve displays
the same general conformation as the
settling curve presented for algal
removal by Williamson and Swanson (their
Figure 3). Dinsdale and Walsby (1972)
showed that when the blue-green alga,
AHH^^nj^ £i2£-ig.u_a e_, was transferred
from low to high light intensity, in the
presence of carbon dioxide-containing
air, the turgor pressure increased by 100
kilonewtons per square meter or more.
This was sufficient to cause the collapse
of gas vacuoles after which the cells
lost their buoyancy. Because there is no
light present in the rock filter at the
time of algal settling, this fluorometric
88
-------
technique may not be applicable to the
determination of mean settling velocities
for algae in rock filters.
Williamson and Swanson concluded
that settling rates of algal popula-
tions from Veneta lagoon were independent
of dominant species, temperature,
or other environmental conditions. This
appears to be an over simplification of
algal settling mechanisms. Rather it
would suggest that the removal mechanism
of algae in rock filters is not discrete
settling. Therefore, discrete algal
settling would not appear to be a valid
basis for the design of rock filters.
Other settling models should be investi-
gated; however, other biological pro-
cesses may in fact control removal.
REFERENCES
Bella, D. A. 1970. Simulating the
effect of sinking and vertical
mixing on algal population dynamics.
J. Water Poll. Cont. Fed. 42(5-2)
R140.
Boleyn, B. J. 1972. Studies on the
suspension of the marine centric
diatom J3.i^t.y_lum _b_rij^litwe^lJLj. (West)
Grunow. Int. Rev. Gesamten Hydro-
biol. 57:585-597.
Dinsdale, M. T., and A. E. Walsby. 1972.
The interrelations of cell turgor
pressure, gas-vacuo1 ation and
buoyancy in a blue-green alga. J.
Exp. Bot. 23:561-570.
Eppley, R. W., R. W. Holmes, and J. D. H.
Strickland. 1967. Sinking rates
of marine phytoplankton measured
with a fluorometer. J. Exp. Mar.
Biol. Ecol. 1:191-208.
Fogg, G. E., W. D. P. Stewart, P. Fay,
and A. E. Walsby. 1973. The
blue-green algae. Academic Press,
Inc. London, 459 p.
Kiefer, D. A. 1973- Chlorophyll a
fluorescence in marine centric
diatoms: Responses of chloroplasts
to light and nutrient stress. Mar.
Biol. 23:39-46.
Smayda, T. J. 1970. The suspension and
sinking of phytoplankton in the sea.
Oceangr. Mar. Biol. Annu. Rev.
8:353-414.
Smayda, T. J. 1974. Some experiments on
sinking characteristics of two
freshwater diatoms. Limnol. and
Oceanogr.' 19:628-635.
Smayda, T. J., and B. J. Boleyn. 1965.
Experimental observations on the
flotation of marine diatoms. 1.
Thalassiosir a cv. H_ajia, Thalas-
ahd NiFzchia seriata.
siosira
Limnol.
rotula
and Oceanogr.
10:499-509.
Smayda, T. J., and B. J. Boleyn. 1966.
Experimental observations on the
flotation of marine diatoms. 2.
Skeletonema cpjst.a^tum and Rhizo-
L imnol. and
Oceanogr. 11:18"~-34.
Titman, D., and P. Kilham. 1976.
Sinking in freshwater phytoplankton:
Some ecological implications of cell
nutrient status and physical
mixing processes. Limnol. and
Oceanogr. 21(3):409-417.
89
-------
AUTHOR'S RESPONSE TO COMMENTS BY M. L. CLEAVE
Kenneth J. Williamson and
Gregory R. Swanson
The authors wish to thank Ms.
Cleave for her comments regarding "Field
Evaluation of Rock Filters for Removal of
Algae from Lagoon Effluents." We agree
that settling may not be the only algal
entrapment mechanism in rock filters, but
maintain that settling is the primary
mechanism. Clearly, many biological and
physical removal mechanisms are occurring
in this treatment system.
Although limited data exist on
the variation of algal species in lagoons
by season and geographical location,
it appears that the predominant algae
are nonmotile green algae. Allen (1955),
for example, surveyed several California
lagoons over a two year period and
found Chlorella and S£ejnj|^Eimu_s to be
usually dominant. These algae depend
upon wind-induced circulation to maintain
themselves in the photic zone and will
settle under quiescent conditions, (Fogg,
1975). Stutz-McDonald and Williamson
(1978) measured mean settling velocities
on pure cultures of Scenedesmus acumina-
tus Lager and Chlorella vulgar is Beij, as
0.26 and 0.14 m/day, respectively, at
21°C. Settling rates were dependent on
temperature as expected; however, neither
aerobic dark nor anaerobic dark incuba-
tion significantly affected settling
rates.
Blue-green algae, such as Micro-
£illi£> occur to a minor extent in
lagoons during most of the year but,
under the right environmental conditions,
may undergo massive blooms in hot, summer
months. This was the case at the Veneta
lagoon this past summer. These algae
generally contain gas vacuoles for
buoyancy regulation. Although the mechan-
ism regulating the formation of gas
vacuoles is not entirely clear, gas
vacuoles develop most abundantly (causing
flotation) in dim light and collapse as a
result of photosynthesis, often resulting
in a diurnal up-and-down movement. Also,
higher concentrations of nutrients may
favor gas vacuole formation (Fogg et
al., 1973). Under the dark, nutrient-
rich conditions which exist in the rock
filter, therefore, evidence indicates
that gas vacuole formation and subsequent
flotation could occur.
Physical observation of recent
fluorometric settling tests on Veneta
lagoon samples with M_i££oc^y_sj.i.j5 f los-
aquae still predominating show that most
of the algae depart from the optical
window by flotation to the surface rather
than settling. It therefore appears that
the entrapment mechanism for these algae
is probably natural biological flotation
rather than settling. This phenomenon
can be viewed essentially as inverse
settling in that these algae are trapped
below the rocks in their attempt to rise,
where they eventually die and decay.
Also, in support of this hypothesis, a
recent physical investigation of the
rocks at and below the water surface in
the rock filter showed that algal re-
sidues can now be found on the bottom
surfaces of the rocks and that a brown
scum layer (1-4 mm thick) of algal
residue has formed at the water surface.
Phytoflagellates (motile algae) such
as Euglena and Chlamydomonas are often
dominant at the lagoon edges, where
little mixing occurs, but generally
comprise only a small part of the total
algal population (Allen, 1955). During
the two sampling periods at the Veneta
lagoon when phytof1 age11 ates were
dominant (March and April, 1978) the
relative abundance indices indicated
that these algae were removed as well as,
or better than other algal species
in passing through the rock filter. The
removal mechanism for phytoflagellates,
however, is not clear. Dinoflagellates
studied by Eppley et al. (1968) were
found to swim at rates of 1 to 2 meters
per hour, a more than sufficient rate
to escape settling. However, these
species may lose their motility and
settle under extended dark conditions
present in the rock filter.
In terms of the total removal
mechanism, the rock filter can be likened
to a clarifier used in large-scale
wastewater treatment. In a clarifier,
the detention time provided allows
settleable solids to settle and floatable
solids to rise to the surface. In the
rock filter, nonmotile green algae will
settle and blue-green algae with gas
vacuoles will rise. The major difference
90
-------
is that the rocks in the rock filter
reduce the settling or rising distance to
a few centimeters. Because the settle-
able algae generally are dominant and
because the very low settling velocities
associated with these algae probably
control rock filter performance in most
instances, a settling model appears to be
appropriate for design of rock filters.
Such a model will not predict rock filter
performance when blue-green algae are
dominant in the lagoon, no more than
settling models for clarifiers predict
removal rates under conditions of bulking
or rising sludge.
The authors must disagree with Ms.
Cleave's contention that the fluorometric
technique is not appropriate for mea-
suring algal settling velocities. While
approximate and not all-inclusive of
algal species, the settling velocities
obtained appear to be reasonable and
correlate well with removal efficiencies
obtained in both the full-scale and the
pilot-scale rock filters. The data
presented by Ms. Cleave on reduction in
fluorescence due to movement and redis-
tribution of chloroplasts offers no
explanation of settling curves obtained
with the fluorometer. On several occa-
sions, the samples have been removed from
the fluorometer following settling tests,
remixed, and then replaced. The fluores-
cence reading obtained by this test has
always been nearly equal to the initial
fluorescence reading.
REFERENCES
Allen, M. B. 1955. General Features of
Algal Growth in Sewage Oxidation
Ponds. California State Water
Pollution Central Board, Publication
No. 13.
Fogg, G. E. 1975. Algal Cultures
and Phytoplankton Ecology. Univer-
sity of Wisconsin, Madison, WI.
Stutz-McDonald, S. E., and If. J. William-
son. Settling Rates of Algae from
Wastewater Lagoons, Paper submitted
for publication to the Environmental
Engineering Div., ASCE.
Fogg, G. E., W. D. P. Stewart, P. Fay,
and A. E. Walsby. 1973. The Blue-
Green Algae. Academic Press, London.
91
-------
MICROSCREENING AND OTHER PHYSICAL-CHEMICAL
TECHNIQUES FOR ALGAE REMOVAL
Richard A. Kormanik and Joe Bob Cravens*
INTRODUCTION
Much research has been conducted
utilizing dissolved air flotation or
various types of sand filtration tech-
niques to remove algae from lagoons
during the warm months of the years.
Several full scale installations have
been built using dissolved air flotation
(DAF) with chemical coagulation for
the removal of algae from ponds. The
most recent installation using DAF
is Sunnyvale, California. Operating
experience at this time is not available.
DAF units have been in operation for
several years, removing algae at a
lagooning operation in Stockton, Califor-
nia; however, exorbitant operating
costs are plaguing that operation.
The writers of this text have
conducted DAF studies as well as micro-
screening studies for the removal of
algae from lagoons. Historically,
DAF has been proven to be an effective
means of removing algae from lagoon
effluent with the use of alum as a
coagulant. However, this method has
shown to have expensive operating costs
because of the need for chemical feed
systems as well as a method for disposing
of the algae/alum sludge.
An alternative to DAF which was
thoroughly investigated in the field,
is microscreening using 1 micron poly-
ester fabric (1). Work done by Kormanik
and Cravens (2) describes full scale
field research done using microscreen-
ing with 1 micron polyester fabric.
Previous investigations using micro-
screens were conducted using 23 and 25
micron stainless steel media. Golueke
et al. (3) conducted pilot-plant studies;
•Richard A. Kormanik is Marketing
Group Manager, Envirex, Waukesha,
Wisconsin, and Joe Bob Cravens is En-
vironmental Research Engineer, Rexnord
Inc., Milwaukee, Wisconsin.
however, removal efficiencies were
nominal. Drum speeds were 10, 20, and 30
rpm.1 The algae species most predominant
in lagoons are Scenedesmus, Chlorella,
and ^hjjsn^djjmonajs (see Figure 13 for
algae bioassays).
In 1975, Caldwell et al. (4) and
Parker (5) tested microscreening on
an oxidation pond effluent; however,
C_hjlo.re_l_l_a and Sc^enedjjjsmujs algae were
the predominant species present. Typi-
cally, the size distribution range
for these species is 1-5 micron; thus,
results were marginal when using the
23 micron media.
Rupke and Chisholm (6) reported the
use of a microscreen pilot unit with
23 micron stainless steel media to
upgrade sewage lagoon effluents. During
July through September SS reductions were
from 20 to 50 percent and BOD reductions
were 10 to 20 percent without coagulants.
With coagulants such as alum, ferric
chloride, or polyelectrolytes, suspended
solids capture was as high as 70 percent
SS.
Essentially algae are present in
ponds in two general classifications:
Chlorophyta (Green)
£.a^ft°Phy^ta (Blue Green or
mat formers)
Each of the groups found in lagoons
contain free swimmers and nonmobile
species and are in size range of 1 to 10
microns.
Algae growth in ponds vary in
quantity and specie. During ideal
pond conditions, green algae are pre-
dominant. These algae are more uniformly
dispersed throughout the pond. Thus, the
ideal symbiotic relationship is achieved
too
^Microscreen submergence time is
short at speeds of 10-30 rpm.
92
-------
when nutrients released via bacterial
decomposition are assimilated by the
algae. In turn the algae release oxygen
via photosynthesis and support aerobic
decomposition.
Blue green algae form in stagnant
pond areas, or during organic shock
loading periods. These floating mats
minimize sunlight penetration and
retard the desired green algae growth.
The floating mats entrap organics,
dead algae, etc.., and the characteristic
"pig pen" odors result.
Diurnally, algae tend to concentrate
near the surface during sunlight produc-
tive hours and die off and settle out
during the night.
Again, Figure 13 illustrates typical
green and blue green algae species
in ponds. Note the typical size, rang-
ing, in general, from 1-10 microns.
Since numerous cell fragments and juve-
nile algae are present, effective
removal via microscreening requires the 1
micron media size.
In 1976 Envirex initiated a field
test program using a 4 foot diameter
by 2 foot long trailer-mounted micro-
screen. The unit is fully automated,
including on-line suspended solids
monitoring and recording meters for
influent and effluent. Hydraulically,
the unit can handle 10-200 gpm, an
appropriate range for 1, 6, 10, and 21
micron polyester media (Figures 1
and 2).
Figure 3 illustrates the polyester
media, magnified 500 times, as com-
pared to Figure 4, stainless steel media.
The polyester media is suited for
high headloss (12" or greater), is not
subject to fatigue, and is inert to
chlorination required for slime control.
The polyester has a consistent weave for
uniform aperture size with maximum open
areas.
To date extensive tests have been
conducted at seven pond sites. Table
4 is a summary of the test program,
identifying microscreen influent and
effluent SS and BOD concentrations.
At one of the field sites, DAF and
microscreening were investigated and
compared. Table 1 shows this comparison.
Both processes obtain a 30/30 (BOD/SS)
standard. The costs for these two
process approaches are compared later in
this text. Table 1 also shows typical
experienced operating conditions for the
DAF. The results of both types of
processes show that a 30/30 effluent can
be obtained.
One interesting observation was the
high pH fluctuation over a 24-hour
period. Figure 5 shows observed pH
variation. What is significant is
that the alum dosage must be varied to
meet the variations in pH as well as
the amount of suspended solids (algae).
This dual process variation causes
significant operating expenses as ex-
perienced by other installations.
MICROSCREENING
Kormanik and Cravens (1,2) have
conducted 2 years of full scale field
studies using microscreens for the
removal of algae from lagoons. Figures
6, 7, 8, 9, 10, 11, and 12 summarize the
additional field studies for the removal
of algae (as recorded as suspended
solids) as well as the BOD associated
with the algae. These extensive studies
using a full scale microscreen have shown
that the removal of algae using 1 micron
polyester fabric is a viable process
alternative for the removal of algae.
At one of the sites researched,
Peoples and Cravens (7) conducted tests
and comparative data were obtained using
microscreening and existing site pressure
filters. Table 2 shows the comparative
results. Here microscreening is shown to
be a more effective means of removing SS
and the associated BOD. Table 3 shows
the SS/BOD relationships before and after
microscreening. It can be noted that from
all of the sites researched, it appears
that significant algae removal (measured
as SS) must be attained in order to
obtain a BOD level of 30 mg/1. Note that
only one lagoon tested (Site No. 6) had
an acceptable BOD/SS (30/90). Table 4
shows tabular results of all of the
lagoons tested for algae removal. This
study has shown that microscreening
with 1 micron polyester fabric is a
process alternative to DAF and sand
filtration. In addition, no operational
problems were encountered at any of the
sites tested. This process success, as
well as the ease of operation, will show
the cost effectiveness of the microscreen
for algae removal.
COST EFFECTIVE ANALYSIS
As mentioned before, dissolved air
flotation (DAF) with alum has been
shown to be a successful process for the
removal of algae. The 2 year study
(1,2) using microscreening with 1 micron
polyester fabric as presented here,
shows that it, too, is a process alter-
native. What is necessary is to dem-
onstrate which alternative is cost
effective for the removal of algae.
93
-------
Figure 1. Microscreen test van at a typical lagoon site.
Figure 2, Envirex 4 foot diameter x 2 foot long microscreen.
94
-------
Figure 3. Electron-photomicrograph 21 micron polyester Figure 4.
media (500X).
Electron-photomicrograph 21 micron stainless
steel media (500X).
-------
Table 1. Summary of side by side microscreen vs. dissolved air flotation continuous
24 hour runs.
Dissolved Air
Flotation
Operating Conditions
Pond
Effluent (mg/1)
T-BOD/TSS
Effluent (mg/1)
DAF
T-BOD/TSS
MICROSCREEN
T-BOD/TSS
100 mg/1 ALUM
NO FLOCCULATION
257. RECYCLE
OVERFLOW RATE 2 gpm/ft'
29/37
9/12
23/4
100 mg/1 ALUM
NO FLOCCULATION
257. RECYCLE
3 gpm/ft2
35/47
13/23
23/19
100 mg/1 ALUM
11 MIN. FLOCCULATION
257o RECYCLE
3.4 gpm/ft2
47/61
—/23
4/14
145 mg/1 ALUM
10.5 MIN. FLOCCULATION
197» RECYCLE
3.2 gpm/ft2
16/20
3/17
100 mg/1 ALUM
19 MIN. FLOCCULATION
257o RECYCLE
2 gpm/ft2
42/58
15/20
33/20
100 mg/1 ALUM
3 mg/1 POLYMER
7.5 MIN. FLOCCULATION
20% RECYCLE
3.6 gpm/ft2
44/34
SOLUBLE
BOD 18
9/4
SOLUBLE
BOD 4
29/10
SOLUBLE
BOD 4
Table 2. Summary of side by side microscreen vs. pressure filter continuous 24
hour test runs.
Hydraulic Loading
Suspended Solids (mg/1)
Run
Number
1
2
3
4
5
Microscreen
Influent
Source
Polishing Pond
Effluent
Polishing Pond
Polishing Pond
Polishing Pond
Polishing Pond
(gpm/t
Microscreen
2.40
2.90
1.65
1.72
2.50
t > I
Pressure
Filter
2.06
1.93
1.93
1.93
licroscreen
& Pressure
Filter
Influent
29
27
19
40
28
Micro-
screen
Effluent
7
14
4
4
10
Pressure
Filter
Effluent
21
24
13
22
24
96
-------
11.0
10.0
9.0
pH
8.0
7.0
6.0
J_
_L
_L
JL
J
0
8:20 PM
8 12 16 20 24
6:20 AM 12:00 AM 8:20 PM
TIME (HOURS)
Figure 5. pH vs. time at Gardendale, South Carolina.
100
80
vt
Q
8 60
O
0
z
111
Q.
IA
3
40
< 20
O
ADEL, GEORGIA
AVERAGE LAGOON EFFLUENT INTO MICROSCREEN 69 mg/l
AVERAGE MICROSCREEN EFFLUENT 9 mg/l
0 10 20 30 40 50 60
7:OOPM NOON NOON 11:00 PM
TIME (HOURS)
Figure 6. Microscreen influent and effluent suspended solids vs. time using 1 micron
media.
97
-------
g 80
O
O 60
O
III
O
5 4°
M
3
O
20
OWASSO, OKLAHOMA
AVERAGE LAGOON EFFLUENT INTO MICROSCREEN 58 mg/l
AVERAGE MICROSCREEN EFFLUENT 15 mg/l
0 10 20 30 40 50 60
6:00 PM NOON NOON 9:00 PM
TIME (HOURS)
Figure 7. Microscreen influent and effluent suspended solids vs. time using 1 micron
media.
GREENVILLE, ALABAMA
AVERAGE LAGOON EFFLUENT INTO MICROSCREEN 44 mg/l
AVERAGE MICROSCREEN EFFLUENT 12 mg/l
40 50
NOON 2:00 AM
TIME (HOURS)
Figure 8. Microscreen influent and effluent suspended solids vs. time using 1 micron
media.
98
-------
CAMDEN, SOUTH CAROLINA
in
O
O 250
3 200
O
jjj ISO
(A
100
50
AVERAGE LAGOON EFFLUENT
INTO MICROSCREEN 126 mg/l
AVERAGE MICROSCREEN EFFLUENT 19 mg/l
8:20PM 4:20 AM 11:00 AM
TIME (HOURS)
6:20 PM
Figure 9- Microscreen influent and effluent suspended solids and pH vs. time using
1 micron media.
I
M
O
80
O 60
O
iii
O
1 40
M
9
M
I"
GERING, NEBRASKA
AVERAGE LAGOON EFFLUENT INTO MICROSCREEN
44 mg/l
AVERAGE MICROSCREEN EFFLUENT 13 mg/l
J I 1 L
0 20 40
5:00 PM NOON NOON
TIME (HOURS)
60 80
NOON 6:00 PM
Figure 10. Microscreen influent and effluent solids vs. time using 1 micron media.
99
-------
80
o
3 60
o
tf»
Q
0
z
III
tf)
3
40
BLUE SPRINGS, MISSOURI
AVERAGE LAGOON EFFLUENT INTO MICROSCREEN 64 mg/l
AVERAGE MICROSCREEN EFFLUENT 22 mg/l
0 10 20
10:30 PM NOON
30 40 SO 60 70
NOON NOON
TIME (HOURS)
80
90
Figure 11. Microscreen influent and effluent solids vs. time using 1 micron media.
40
8 30
o
in 20
O
3 10
ml
O
GUMMING, GEORGIA
AVERAGE LAGOON EFFLUENT INTO MICROSCREEN
— 26 mg/l
AVERAGE MICROSCREEN EFFLUENT 6 mg/l
_L
0 20
6:00 PM NOON
40 60 80 100
NOON NOON NOON 10:00 PM
TIME (HOURS)
Figure 12. Microscreen influent and effluent solids vs. time using 1 micron media.
100
-------
Table 3. Comparison of lagoon and micro-
screen effluents BOD/SS ratios
vs. EPA lagoon standards.
Site
1
2
3
4
5
6
Actual
Pond
Discharge
(Micro -
screen
influent)
43/51
38/100
61/81
44/83
50/72
30/59
Ratio
0.84
0.38
0.75
0.53
0.70
0.51
Required
for
EPA
Standard3
30/36
30/79
30/40
30/57
30/43
30/59
Micro-
screen
Effluent
Actually
Achieved
12/19
•23/21
19/22
14/11
28/9
18/15
30 mg/1 BOD currently required for
lagoon effluent discharges less than 2
mgd.
Table 4. Summary of the average micro-
screen influent and effluent
total suspended solids and
T-BOD
Figure
Number
6
7
8
9
10
11
12
Lagoon Effluent
(Microscreen
Influent)
TSS (mg/l)/T-BOD5
69/72
58/30
44/45
126/38
44/ —
64/32
26 / —
Microscreen
Effluent
TSS (mg/l)/T-BOD5
9/9
15/15
12/14
19/23
13/ —
22/16
6/ —
Table 5. Cost effective analysis for 1.7
mgd lagoon upgrade--microscreen
option.
Capital Costs
1. Microscreen equipment and
chamber (installed) $595,000
2. Laboratory, office, control
room, etc. $112,000
3. Chlorination $ 35,000
4. Bar screens $ 50,000
5. Aeration addition $126,000
6. Piping and valves $120,000
7. Pump station $ 75,000
8. Grading and paving $ 20,000
9. Electrical $ 25,000
10. Miscellaneous $ 60,000
Total Construction
Estimate
Engineering, legal
fees, etc. (20%)
Total Project Cost
_Say_
$1,218,000
$ 243,000
$1,463,600
$1.500.000
B. P. Barber and Associates, con-
ducted pilot studies with DAF and micro-
screens at a 1.7 mg/1 lagoon which needed
total upgrading (8). Their findings
are shown in Tables 5, 6, and 7. As can
be seen, microscreening is by far
more cost effective than DAF or building
a new mechanical plant. What is
interesting to note here, is the signifi-
cantly higher cost for a system utilizing
DAF for algae removal. The vast majority
of the additional total cost is for
operating cost due to the requirements
for alum addition and the removal of the
alum/algae sludge. With microscreens the
algae are only returned at the inlet of
Table 6. Cost effective analysis for 1.7
mgd lagoon upgrade—micros creen
option.
Operation and Maintenance
1. Power
6 drives drawing 5 hp 30 hp
Backwash pump 5 hp
Aerators 6 at 15 hp
Pump station
135 hp at $200
Manpower
1 full time at 12,000
1 part time at 5,000
3. Materials and Supplies
$27,000
$17,000
Grid replacement (once/5 years)
160 at $30 $ 6,000
Motor, miscellaneous, etc. $ 5,000
4. Chlorination
2.1 cents/1000 gallons $13,000
5. Miscellaneous
Say $ 3,000
$71,000/Year
Table 1, Cost effective analysis summary
1.7 mgd lagoon upgrade.
A. Microscreen Option:
Total Present Worth
$1,500,000
(71,000 x 11.47)
B. New Activated Sludge
Plant (Orbal):
Total Present Worth
C. Dissolved Air Flotation
(From Pilot Study):
Total Present Worth
$2,314,370
$2,718,658
$3,765,000
101
-------
GREEN ALGAE Chlorophytea
observed size
Chlorella UI200 ]
(Nonmobile
Scenedesmus (x 1000)
(Nonmobile)
Euglena (x430)
(Free Swimmer)
Chlamydomonas (x 1300)
(Free Swimmer- Green)
BLUE-GREEN ALGAE Cyanophyta
Selenastrum (x IOOO)
(Nonmobile)
Spirogyra
(xlOOO)
(Green Algae)
Merismopedia (x600)
Oscillatoria (x 825)
Figure 13. Typical algae species present in other oxidation ponds that may appear
on a seasonal basis. (NOTE: 10 micron scale is shown in each case for
the appropriate magnification).
102
-------
the lagoon. This cost analysis tends to
bear out the reason for the high operat-
ing costs at the Stockton installation
which use DAF for algae removal.
CONCLUSIONS
1. Microscreening utilizating 1
micron polyester fabric effectively
removes algae as demonstrated at eight
lagoon sites and achieved a minimum of
a 30/30 effluent or better at all sites
researched.
2. Microscreening has been shown to
require only minimum operating experience
or expertise; thus, allowing for low
operating expense. Other reported
experience on this research (1,2) shows
microscreening effectiveness to be
independent of pH or volumes of algae
(measured as suspended solids).
3. The financial analysis conducted
by B. P. Barber and Associates (8)
has shown microscreening to be very cost
effective for the removal of algae.
REFERENCES CITED
1- Cravens, J. B., and R. A. Kormanik.
The Upgrading of Lagoons and Waste-
water Treatment Plants via Micro-
screening. Presented 5!st Annual
Meeting of the CSWPCF, May 1978,
Bloomington, Minnesota.
2. Kormanik, R. A., and J. B. Cravens.
Removal of Algae by Microscreening.
Submitted for publication, Water and
Waste Engineering.
Golueke, C. G., and W. J. Oswald.
Harvesting and Processing Sewage
Grown Planktonic Algae. JWPCF,
37:471-498 (1965).
Caldwell, D. H., D. S. Parker, and
W. R. Uhte. Upgrading Lagoons.
Environmental Protection Agency
Technology Transfer, Seminar Publi-
cation, June 1977.
Parker, D. S. Performance of
Alternative Algae Removal Systems.
Presented at Symposium No. ^9, Ponds
as a Wastewater Treatment Alterna-
tive, University of Texas at Austin,
July 22-24, 1975.
Rupke, J. W. G., and K. Chisholm.
Upgrading of Sewage Lagoon Ef-
fluents. Research Report No.
54:1-27 (1977), Ministry of the
Environment, Ontario, Canada.
Peoples, R. F., and J. B. Cravens.
Upgrading Secondary Clarifier
and Algae Pond Effluent via New 1
Micron Screen. Submitted for
publication, Pollution Engineering.
Engineering Report. Recommended
Design for the City of Camden, S.
C. Wastewater Treatment Facility.
B. P. Barber & Associates Inc. ,
Consulting Engineers.
103
-------
POND ISOLATION AND PHASE ISOLATION FOR CONTROL OF
SUSPENDED SOLIDS CONCENTRATION IN SEWAGE
OXIDATION POND EFFLUENTS
Ben L. Koopman, John R. Benemann, and W. J. Oswald*
INTRODUCTION
During the 30 years of lagoon
research that has followed the earliest
papers of the 1940s and 1950s (1, 2, 3)
it has become amply evident that over-
flowing waste ponds, i.e., waste ponds
which discharge effluents, should
be comprised of more than one unit in
series. Indeed, in climates having
well defined seasons, a case has been
made for a minimum of four waste ponds
in series safeguarded from thermal
short-circuiting influent to effluent
by alternating low-level and high-level
interpond transfer systems and by care-
fully locating their horizontal positions
with regard to winds and currents
(4). Once a multi-pond sequence is
accepted as a design principle, the
opportunity arises to design each pond in
the series to optimize one or more
stages in the series which are known to
occur. We have previously used the
term "phase isolation" to describe an
environment for each distinct phase
of the overall treatment process having
special requirements (5).
As has been emphasized in several
previous papers (6, 7), processes (e.g.
phases) which can be selectively enhanced
in specially designed ponds are grit and
grease removal; primary sedimentation;
methane fermentation of settled organic
solids; biological oxidation of soluble
organics; photosynthetic oxygen produc-
tion; nutrient and toxicant removal;
separation of algae; and disinfection.
When ponds which perform these functions
are placed in series, we refer to the
entire process as "integrated ponding."
*Ben L. Koopman, John R. Benemann,
and W. J. Oswald are respectively,
Graduate Research Engineer, Associate
Research Biochemist, and Professor of
Sanitary Engineering and Public Health,
University of California, Berkeley,
California.
The advantage of integrated ponding is
that it is more effective and efficient,
achieving higher treatment standards in
smaller areas than standard facultative
pond systems. This is due to the in-
creased process rates achievable when
design is optimized for each particular
phase. At present design parameters
for standard pond systems are not well
defined (8) and designs for integrated
ponding must to a considerable extent be
based on standard pond design cri-
teria. Thus the design criteria and
formulae for integrated ponding sys-
tems are not yet perfected and require
further R & D. Nevertheless, it is
already possible to apply the integrated
ponding concept to the design of waste-
water treatment facilities. Each of the
processes mentioned above can be enhanced
through specific pond design details and
each can contribute significantly to
improvement in the final effluent from
ponds. Not all the phases listed can or
need be isolated from each other, and
separation between phases is not perfect.
Integrated ponding involves a combination
of anaerobic, facultative, high-rate,
settling, polishing, and holding ponds.
In the simplest configuration of in-
tegrated ponds, the first of the above
processes--primary sedimentation, grit
and grease removal, methane fermenta-
tion and some oxidation—occur in the
primary pond of the series which is
a highly loaded facultative pond.
Biological oxidation and photosynthetic
oxygen production occur simultaneously in
the second pond of the sequence, termed
the algal growth or high-rate pond. The
recirculation of oxygenated effluents
with high pH from the algal growth pond
to the plant influent may be used to
condition the influent and improve the
performance of the facultative pond.
Removal through sedimentation of algae is
best accomplished in a third stage of the
process, the sedimentation phase, in an
algal settling pond. A final polishing-
holding pond in the sequence is recom-
mended but not absolutely required to
allow nutrient stripping, additional
algal sedimentation, to permit further
104
-------
disinfection, and to provide storage for
controlled discharge and/or land applica-
tion of the treated waste.
In this paper we present recent
experience with the operation of an
algal sedimentation pond at Woodland,
California. This system was initiated
by Hiatt, Engineer of the City of Wood-
land, who has reported (9) the produc-
tion of high quality effluent by a system
involving conventional facultative
ponds followed by a draw and fill oper-
ated secondary pond. The function
of the secondary, so called "phase
isolation" pond was to accomplish removal
of algae from the facultative effluent.
It was not known by what mechanism
this removal occurred although the
isolation of the facultative effluent
from further sewage inflow until the
algae disappeared was deemed essential.
The novelty of this treatment scheme led
us to conduct a 1 year monitoring pro-
gram of its application at Woodland,
California, to treat 1 mgd of sewage.
This study has now been extended, but is
nearly completed and preliminary results
can be reported. To avoid confusion we
have suggested that the term "pond
isolation" be applied to the removal of
algae from facultative pond effluents on
a batch basis in an isolated secondary
pond.
Results from Woodland are compared
with those obtained in integrated
pond systems. Recent experiences at our
laboratory at Richmond, California,
in the removal of algae by microstraining
are also discussed.
POND ISOLATION STUDIES AT WOODLAND
A still ongoing study of the pond
isolation process has been carried
out by our group under sponsorship and in
conjunction with the City of Wood-
land and the California Water Resources
Control Board during 1977 and 1978 using
existing ponds of the City of Woodland.
Pertinent details of that study drawn
from our reports to the City of Woodland
and the California Water Resources
Control Board (10) are outlined here.
Climate
The City of Woodland is located in
North Central California. This area
has warm, dry summers and moderately
warm, wet winters. Weekly averages
for insolation, air temperature,_and wind
movement are presented in Figure 1.
Data for rainfall, evaporation, and net
evaporation are presented in Table
1. Daily isolation averaged greater than
500 langleys between April and Sep-
tember, but rarely rose above 200 lang-
Table 1. Rainfall, evaporation, and net
evaporation in Woodland area.3
Precipi- Evapo- Net
Month tation ration Evaporation
en) ctn cm
April 1977
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Jan. 1978
T
2.8
T
T
-0-
1.8
0.6
7.0
10.1
24.7
24.6
19.0
32.1
33.2
27.9
22.1
16.2
10.0
3.8
2.5
24.6
16.2
32.1
33.2
27.9
20.3
15.6
3.0
<6.3>
<22.2>
aU.C. Davis Meteorological Station.
leys in December and January. Net
pan evaporation was greatest in June and
July (exeeding 30 cm per month) and
averaged over 25 cm per month between
April and October. Significant amounts
of rain fell in November and continued
intermittently throughout December
and January.
As indicated in Figure 1, the
Woodland area was moderately windy
during the entire investigation and
especially so in April 1977 and January
1978 when average wind movements of over
250 km per day were recorded. Average
maximum air temperatures (Figure 1)
exceeded 30°C from June into October.
Average minimum air temperatures were
usually about 15°C below the maximums.
Water_S_£pply and Waste-
water Composition
The City of Woodland obtains its
water from deep wells. A typical
chemical analysis of the domestic water
supply is given in Table 2.
Woodland's wastewater is principally
domestic in origin. Industrial waste-
waters are treated in separate facilities
from the domestic wastewater. Observa-
tions of the domestic sewage during the
canning season indicated, however, that
some tomato processing wastes were
discharged into the domestic sewer. A
typical analysis of Woodland's domestic
wastewater is given in Table 3.
pondjLng System
The Woodland facultative-isolation
ponding system consists of six, square-
shaped, 1.9 ha ponds. These ponds were
excavated from alkali-type soil and were
not lined. The layout and flow schemes
for these ponds are shown in Figure 2.
105
-------
Ponds 1, 2, and 3 were about 2.7 m in
depth and Pond 6 was about 1.8 m deep.
Four of the ponds, numbers 1, 2, 3, and 6
were loaded with raw sewage. Sewage was
introduced by way of bottom inlets
located about 40 m from the closest pond
levees. Pond 5 was normally operated as
the isolation pond. After being partial-
ly drained, it could be filled again
with effluents from Ponds 1, 2, and 6.
Because of hydraulic constraints, Pond
3 could not discharge to Pond 5 and,
therefore, was usually allowed to over-
flow continuously into a drainage chan-
nel. During a typical discharge period,
about the upper 1/8 m of water depth
could be withdrawn from each facultative
pond. The isolation pond typically
reached a depth of 1.5 m after being
filled.
Once in the isolation pond, the
facultative effluent was held without
further sewage inflows until a marked
decline in algal concentration oc-
curred. When the TSS concentration in
the isolation pond dropped below 30
mg/1 or appeared to have reached a
minimum, the supernatant (usually 0.4-
0.5 m of depth) was discharged. The
supernatant was withdrawn via a concrete
pipe located at the NW corner of the
pond. The draining period required
3 to 4 days. About 1.1 m of water depth
MAR APR MAY JUN JUL AUC SEP OCT NOV DEC JAN FEB
Firurc 1. Weekly average wind movement, air temperature, and insolation in Woodland
area.
106
-------
Table 2. Typical chemical analysis Wood-
land domestic water supply (6) .
Total solids
Hardness
Bicarbonate
Alkalinity
Ca
Mg
Fe
Mn
Na
K
Chlorides
Sulfates
Fluorides
Nitrate-Nitrite
Specific Conductance
pH
As
B
Cu
Pb
Se
Zn
Hg
Color
Odor
Temperature
Turbidity
368 mg/1
248
258
258
41.5
30.5
<0.02
<0.02
50
2.0
58
34
0.5
3
484 micromhos/cm
8.2
<0.006 mg/1
1
<0.005
<0.005
0.005
0.008
<0.002
<5 units
None
65°F
<1 unit
remained in the isolation pond after
discharge because of the vertical place-
ment of the pipe. When the drain
cycle was completed, flashboard risers
connecting Ponds 2 and 6 to the iso-
lation pond were opened. Effluent from
Pond 1 first flowed into Pond 6 before
reaching the isolation pond. Water
surface elevations between the faculta-
tive and isolation ponds required about 2
days to equalize and, thus, complete a
fill cycle.
Table 3.
Typical analysis--Woodland do-
mestic wastewater.
COD
total
filtered
particulate
BOD5
Nitrogen
total
ammonia
nitrate + nitrite
organic
Total Phosphate
Total Iron
364 mg/1
137
227
184
39.1
26.6
0.1
12.4
10.6
2.2
90 cm I
POND EFFLUENT CANAL 1
9
/T
I 3
FACULTATIVE
Raw sewage inflow
2
FACULTATIVE
~~ — ~~~~^ /
/
\ I
FACULTATIVE
Pond effluent
/\ transfers
^ I t -J
POND EFFLUENT
LIFT STATION
RAW SEWAGE INFLUENT
LIFT STATION
kf-
4
PERCOLATION
5
ISOLATION
60cm
FACULTATIVE
t
NORTH
I cm = 48m
y v
Figure 2. Layout and present flow scheme for
Woodland strong ponds. Redrawn from (11)
107
-------
Sampling Schedule and Locations
Raw Sewage--
The raw sewage was sampled at the
lift station after being screened and
pumped. The lift station was located
about 3 km from the pond system. Three
distinct samples were taken each day
(morning, noon, and afternoon), and
these were composited prior to analysis.
Two or three such composite samples
were obtained each week.
The flowrate of sewage was measured
immediately before reaching the faculta-
tive ponds. The differential pressure
across a Venturi section was sensed by a
mechanical unit^ which recorded the
instantaneous flowrate as well as total-
izing daily flows.
Facultative Pond
Effluents—
The effluents from Ponds 1 and 6,
which reached the isolation pond via
a single transfer structure, were sampled
using an Isco automatic composite-
sampler, Model 1580. The duration of
compositing was limited to about 8
hours daily because of the possibility of
vandalism. Effluent from Pond 2 was
sampled and composited manually. Four
individual samples were taken the
first day of overflow and three on each
day thereafter, over a period of 8
hours.
The volume of effluent represented
by each composite sample was calculated
from the daily changes in water surface
elevations of the ponds sampled. For a
4.9 ha pond, each centimeter of depth
represented about 490 cu m of effluent.
Isolation Pond Effluent--
Effluent samples from the isolation
pond were composited using the Isco
automatic sampler. The sampling period
was approximately 8 hours daily. As
noted above, the volume of effluent
represented by each day's sample was
calculated from the daily change in pond
elevation.
Isolation Pond In Situ
or Offshore Sampling--
Samples of the isolation pond during
non-draining periods were taken either at
the geometric center of the pond or from
the NW corner of the pond near the drain
pipe. In situ samples at the center of
the isolation pond were obtained at 0.30
m intervals using a Van Dorn bottle and
composited to give a water column aver-
^Honeywell Corp., Model No.
Y222(E)1.
age. Offshore samples were taken at a
depth of 0.15 m about one-half meter from
the pond's edge.
Facultative Ponds: Loading
and Effluent Compositions
Raw Sewage Loading Rates--
The BOD5, COD, and total nitrogen
content of the sewage influent to the
facultative ponds is given in Table 4.
BOD5 averaged 238 mg/1 over the re-
porting period, a value considerably
higher than the average BOD5 of 14?
mg/1 reported in 1975 (11). The high
levels of BODc recorded in 1977 were
also characteristic of wastewaters from
other California cities during the
drought of that year. Because of im-
pending water shortages, water conserva-
tion efforts substantially reduced normal
water consumption in the City of Wood-
land .
The highest monthly averages for
BODg were recorded in May and August
when values of 355 mg/1 and 305 mg/1,
respectively, were found,. The high
August 6005 apparently reflected the
contribution of tomato wastes to the
domestic sewage as remnants of tomatoes
were observed in the sewage during
this period.
Total nitrogen averaged 34.9 mg/1,
also a typical value for domestic
sewage. The nitrogen concentrations were
quite uniform except for minimums
of 27.5 mg/1 and 28.5 mg/1 observed in
July and December.
Average total inflow to the faculta-
tive ponds was 4,400 cu m per day,
the same as recorded in 1975. However,
for the three-month period--July-
September—the average flow dropped to
3,750 cu m daily. This drop in the
inflow rate resulted in very small
volumes of overflow from the facultative
ponds because evaporation and percolation
were quite high during this period.
In order to restore a greater volume of
facultative pond effluent, additional
sewage from the lift station was diverted
to the facultative ponds beginning
in October. In response, the inflow rate
increased to an average of 4,800 cu m per
day between October 1977 and January
1978.
Also given in Table 4 are hydraulic,
BODg, and total nitrogen loading rates
to the facultative ponds. These rates
were calculated by dividing the respec-
tive mass loading rates by the total area
of the four facultative ponds receiving
sewage. The hydraulic loading rate
averaged 2.2 cm per day. However, during
the months of July, August, and Septem-
ber, the loading rate dropped to only 1.9
108
-------
Table 4. Rawg sewage loading to Woodland facultative ponds-April 1977 to January
Month
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Jan. 1978
Ave.
Flow
3
m /day
3,700
4,200
5,300
3,000
4,500
3,750
4,800
5,000
4,700
4,700
4,400
COD
mg/1
479
696
393
320
571
472
444
440
346
339
446
BODs
mg/1
246
355
202
165
305
257
255
237
181
193
238
Total
Nitrogen
mg/1
38.9
36.0
37.0
27.5
36.5
35.2
38.5
40.1
28.5
31.4
34.9
Overall Loading
Hydraulic
cm/ day
1.9
2\2
i.'s
2.3
2\5
2.6
2.4
2.4
2.2
BOD5
kg/ha/ day
LI
*-f /
77
/ /
cs
j j
25
71
50
63
61
44
47
54
Rates
Nitrogen
kg/ha/day
7 A
/ . 4
/ . o
in T
1U . i
L 7
H . /.
8 L
O . H-
ft 8
u , o
9 .5
1 0 ^
4.VJ . J
6.9
7^6
7.9
cm per day. Evaporation alone during
this period accounted for 0.7 cm per
day,2 thus reducing the effective
loading rate to 1.2 cm per day. Percola-
tion undoubtedly also removed a signifi-
cant amount of water each day. The net
result was that the quantity of effluent
discharged was insufficient to keep the
isolation pond adequately diluted.
Beginning in October, the hydraulic
loading rate was increased. Between
October and January 1978, the average
hydraulic loading was 2.5 cm per day.
The average 6005 loading rate was
54 kg per ha per day, a value con-
siderably higher than the rate of 44 kg
per ha per day reported for 1975.
This increase was due solely to an
increase in BOD5 concentration as
the flow rates for both years were
similar.
Peak BOD5 loading rates of over 70
kg per ha per day were recorded in
May and August. Although these loadings
were considerably greater than the
average rate of 34 kg per ha per day
allowed for design in most states (12),
there were no odor nuisances or occur-
rences of floating sludge observed
in the ponds.
The average total nitrogen loading
rate to the ponds was 7.9 kg per ha
per day. Peak monthly values of 10.1 and
10.3 kg per ha per day occurred in
June and November, respectively.
2By application of a pan coef-
ficient of 0.75 to the average net
pan evaporation during July-September of
0-90 cm per day.
Performance of Primary Ponds--
The intermittent nature of the
facultative pond overflows facilitated
characterization of these wastes.
Usually only 2 days of sampling were
required to monitor the discharge re-
sulting from 2 to 4 weeks of pond opera-
tion. The compositions of these over-
flows are given in Table 5.
Overflow volumes--Volumes of over-
flow were calculated using observed
changes in pond depth. The processes of
evaporation, percolation, and sewage
inflow continued to affect pond depths
during the discharge periods, but
their combined effects were insignificant
relative to the larger changes in
depth caused by discharge. The combined
losses in facultative pond depths
from discharge were found to be within 10
percent, on the average, of the cor-
responding rise in depth of the isolation
pond.
Between June and August an average
of 20,200 cu m of effluent were dis-
charged to the isolation pond each month.
As no overflows of the isolation pond
occurred during this period, it is
apparent that the combined effects
of evaporation and percolation were
responsible for removing approximately
1.4 cm of water per day. Considering the
average pan evaporation rate for this
period (0.90 cm per day) and a pan
coefficient of 0.75, about 50 per-
cent of this removal can be attributed to
evaporation, with the rest due to
percolation.
The 57,600 cu m of effluent dis-
charged between September 27 and October
4 was due to two factors: (1) four
facultative ponds, rather than three,
contributed effluent and (2) Pond 4,
109
-------
Table 5. Compositions of Woodland facultative ponds' overflows.
Overflow S°ur,ce
Period Pfnds
No.
April
18-20
1977
May
17-18
June
6-7
June
27-28
July
26-27
Aug.
22-23
Sept. 27a
-Oct. 4
Oct.
24-26a
Nov.
28-29
Dec.
21-22
Jan.
17-18
Feb.
8
1978
1&6
2
Comp
1&6
2
Comp
1&6
2
Comp
1&6
2
Comp
1&6
2
Comp
1&6
2
Comp
1,2,3
&6
1,2,3
&6
1&6
2
Comp
1&6
1&6
1&6
2
Comp
Volume
3
m
—
--
--
13,800
8,400
22,200
9,500
7,400
16,900
12,300
9,300
21,600
57,600
24,600
18,000
17,200
35,200
20,100
25,300
14,500
10,100
24,600
Suspended Solids
Totalb
mg/1
139
84
111
68
90
77
66
113
85
76
100
85
75
113
92
111
129
118
133
161
87
82
84
58
33
35
37
36
Volatile0
Algal
mg/1
117
70
93
59
78
67
46
96
66
60
85
69
62
96
77
75
87
80
79
99
49
65
57
46
17
20
29
24
Grazer
mg/1
--
__
11
16
13
13
26
16
3
10
2
1
1
-0-
1
Chloro-
phyll
a
Ug/l
1460
577
1020
631
759
682
548
866
675
424
1120
690
403
1020
674
562
1004
752
891
1070
451
779
612
459
97
195
344
256
COD
BOD5
mg/1
--
__
85
46
70
__
51
39
46
74
--
--
26
18
18
22
20
Total Filtered
mg/1 mg/1
206
178
192
171
109
146
183
190
186
--
--
— _
--
--
125
146
135
124
71
73
79
75
52
64
58
59
28
47
77
37
61
92
60
80
81
54
69
72
59
66
83
67
--
70
39
24
46
33
Nitrogen
• NH3+
NHj
mg/1
0.2
7.5
3.8
0.8
0.3
0.6
0.2
0.1
0.2
0.2
0.3
0.3
0.2
0.3
0.2
0.6
1.9
1.2
2.5
3.6
0.2
1.5
0.8
0.1
0.8
1.8
3.3
2.4
NOjf
N02 Organic
mg/1 mg/1
--
--
--
::
--
T
T
T
0.1
0.1
0.7
0.5
0.6
1.3
1.0
1.1
0.9
1.0
12.0
9.4
10.7
8.7
9.4
9.0
6.5
9.0
7.5
6.5
10.6
8.3
5.6
8.4
6.8
10.4
12.7
11.4
9.6
10.1
6.9
10.2
8.5
7.2
3.1
2.8
3.8
3.2
Total
mg/1
12.2
16.9
14.5
9.5
9.7
9.6
6.7
9.1
7.7
6.7
10.9
8.6
5.8
8.6
7.0
11.0
14.6
12.6
12.2
13.8
7.8
12.2
9.9
8.6
4.9
5.7
8.0
6.6
aOverflows discharged to temporary isolation pond.
^Grazers not included in TSS for June 27-28 and July 26-27 overflows.
CAlgae and grazers separated with 150-ym or 243-ym mesh straining cloth.
NOo and NO^ not included in total-N April-July.
-------
which was completely empty before,
was filled instead of Pond 5, thus
allowing the facultative ponds to be
drawn lower than normal. Again, during
October 24-26, all four facultative
ponds were discharged into Pond 4.
Beginning in November, overflows
were again routed into Pond 5. In
December and January only Ponds 1 and 6
were allowed to discharge into Pond
5 while in November and February, over-
flows from Ponds 1, 2, and 6 were in-
corporated into the fill stream.
.__-The suspended
solids contents of the facultative
pond overflows are shown in Figure 3. In
this figure the total bar height repre-
sents the total suspended solids (TSS)
and the height of the shaded area
gives the volatile suspended solids.
Beginning with the October outflow,
the VSS is divided between algal and
grazer biomass.
Dif ferejTt.jlia_tiioti_b^t_wieeti_ algal and
grazer biomass--Signif leant populations
of grazer organisms including water
fleas (Daphnia), copepods (Cyclops) ,
and rotifers CBrachionus) were often
observed in the ponds.
Initially, no effort was made to
separate the algal grazer biomass.
Beginning June 27, the effluent samples
were prestrained with 243 urn mesh
fabric before making dry weight deter-
minations. Any visible Oscillatoria
filaments retained by the~fTb~FTTSS
J 1
L
>Q
,\
1
" \
\
\
\
\
\
••
'-_ \
\
: \
\
\
\
.J k
6
wss
J 1
3,6
V
s
s
1 1 1
1,2,3,6
5
^ —
$ 1,2,6
^ '
s
•> N
s
;•
x x
x
; 1 .x
-
'1,6
f
U.. .
^
s
\
\
S
X
s
X
\
1,6 '^rt6"
q S ~
•^ X
\ N
1 > 1 ^
APR MAY JUN JUL AU6 SEP OCT NOV DEC JAN FEB
1977 1978
Figure 3. Total, volatile, algal, and grazer suspended solids in Woodland facultative
pond overflows.
Ill
-------
contained no more than 40 mg/1. Effluent
TSS levels were greater than 70 mg/1 in
most cases and equaled or exceeded 100
mg/1 in April, August, September, and
October discharges.
Volatile suspended solids--0n the
average 77 percent of the total sus-
pended solids consisted of volatile
matter. This proportion varied somewhat
between discharges and appeared to
depend, in part, on wind conditions.
Samples taken on windy days contained
finely divided, greyish material probably
comprised of resuspended sediments.
During stormy weather in January and
February, the average effluent-suspended
solids were only 62 percent volatile.
Algal .and grazer volatile suspended
j3oJJLdj>--Asignificant fraction, TT
percent, of the average VSS consisted of
grazer biomass. Concentrations reached
26 mg/1 in October when grazers made up
21 percent of the volatile suspended
solids. Relatively small grazer popula-
tions, averaging less than 2 mg/1, were
observed in December, January, and
February, and comprised 5 percent of the
VSS during that period. Algal biomass in
the January and February overflows was
less than 30 mg/1. All other discharges
contained at least 46 mg/1 algal biomass
with a peak of 99 mg/1 occurring in
October.
Chlorophyll a--Chlorophyl 1 a_ was
used as another index of algal biomass.
It is not contained by the non-photo-
synthetic components of pond ecosystems
but is present in all the pigmented
algae. The chlorophyll a content of
algal cells is subject to variation,
depending on light intensity, nitrogen
availability, cell age, and other physio-
logical factors. However, the median
of a large number of samples is often
found to be about 1 percent of the
ashfree dry weight (13).
Chlorophyll _a correlated linearly
with both the algal suspended solids
(1*2 = 1.0) and the total suspended solids
(r2 = 0.9).
Biochemical oxygen demand (BOD)--The
BODc; measurements were conducted in
the dark to prevent photosynthetic
oxygen production. In 8005 tests of
Woodland's pond effluents, it was ob-
served that algal cells and grazer
organisms usually survived the incubation
period. Therefore, mainly the respi-
ratory oxygen requirements for these
organisms were measured. Relatively
few BODc; assays were made on faculta-
tive pond overflows. Discharges in
December, January, and February contained
less than 30 mg/1. The average 6005 of
the other discharges was 63 mg/1.
Chemical oxygen demand (CODj_--COD
tests were run on filtered samples
of pond effluent in order to provide an
estimate of their soluble organic
strength. The difference between filter-
ed and unfiltered (total) COD gave
the particulate COD, i.e., the COD
contributed by algal biomass. Filtered
COD was lowest in the January and Febru-
ary overflows. The average for these
months was 36 mg/1. Filtered COD was 80
mg/1 in the June 27-28 discharge and
exceeded this value in September. The
average for all other overflows was
65 mg/1. Total COD measurements are
incomplete. Using those available,
the particulate COD is found to have
ranged between 134 mg/1 in April and 32
mg/1 in January.
Nitrogen — The total nitrogen was
determined by summing ammonia-N, ni-
trite plus nitrate-N and orga"nic N. The
highest concentrations of effluent,
total N, exceeding 10 mg/1, occurred in
April and August-October. Only the
January discharge contained less than 5
mg N per liter.
The principal constituent of the
total nitrogen concentration was al-
ways the organically bound nitrogen as
determined by the Kjeldahl test. Organic
nitrogen accounted for 75 percent of the
average total N value in those analyses
for which all constituents were deter-
mined .
Ammonia was the next most important
nitrogen species, occurring at con-
centrations of 0.2 to 3-0 mg/1. In every
discharge except that for January,
ammonia exceeded the sum of nitrite and
nitrate on a nitrogen basis. Ammonia
dropped below 1 mg/1 between May and July
and again from November through January.
Nitrate and nitrite were not measured
before August. Their sum was below 1
mg/1 until December and remained near 1
mg/1 thereafter.
Algal composition of facultative
pond ~ov"eT;TIaw's^"^0?i"e of tTiet"wo a 1 gae
predominant in most overflows was Oscil-
latoria. Oscillatoria is a filamentous,
blue-green alga commonly tychoplanktonic
in nature. Along with many other blue-
greens, Oscillatoria have the ability to
regulate their buoyancy through the use
of intracellular gas vesicles and thus
can migrate vertically in the water
column. The species observed at Woodland
occurred in trichomes about 6 Pm in
diameter and ranging from less than 50
um to several millimeters in length. When
ponds at Woodland were rich in Oscil-
latoria , they appeared turquoise in color
and often exhibited surface scums in
downwind corners.
112
-------
The second predominant -type of algae
has not yet been identified. They
are grass green in color, approximately
spherical in shape, and 3 urn in dia-
meter. Because of their small size and
lack of a distinctive, cup-shaped
chloroplast, they were not believed to be
Chlorella.
The algal compositions of individual
pond discharges differed significantly.
Oscillatoria made up a 41 percent or more
of the total algal biovolume concentra-
tions in Pond 2 effluents, whereas
effluents from Ponds 1 and 6 contained at
the most 23 percent Oscillatoria. The
population of the unidentified green
organism in Ponds 1 and 6 made up an
average of 57 percent of the algal
biovolume while these same algae never
accounted for more than 26 percent of
Pond 2 effluent algal biovolumes.
A detailed account of the algal
species throughout the study is included
in the project reports (10).
Isolation Ponds
Effluent Suspended Solids and Chloro-
phyll--
A graphic overview of the algal
suspended solids (algal SS) and chloro-
phyll a found in the isolation ponds as a
function of time is given in Figure
4. Algal SS, as noted previously, refers
to the volatile suspended solids exclu-
sive of grazer biomass.
The cyclic behavior exhibited in
April, May, and early June corresponds
closely to Hiatt's observations (9).
During these cycles, the jLri situ algal
SS and chlorophyll always fell from the
maxima created by influxes of facul-
tative pond effluent (fills). After the
June 27 fill, however, the algal density
rose and, despite some fluctuations,
continued to increase throughout July and
August and much of September.
A second anomaly occurred coincident
with the growth of algae in the isolation
pond: The increments of depth added by
the June 27, July, and August fills were
removed so fast by evaporation and
percolation that discharges became
impossible, the water levels having
dropped below the elevation of the drain
pipe invert before it was time for the
next fill.
As October approached and no de-
crease in algal density or chance for
discharge were in sight, it was decided
to drastically modify pond operation.
The exact strategy of modification was
much debated, however. One school of
thought held that algal sediments in Pond
5, having built up during previous
years of operation, had begun recyling
nutrients which sustained algal growth.
Thus, it was reasoned that a previously
unused pond should be substituted for the
"aged" isolation pond. A second hy-
pothesis presumed that, because there was
no dilution through the isolation pond,
algal species tolerant of low nutrient
concentrations were able to colonize the
pond in spite of their slow growth rates.
If this hypothesis were true, then
periodic discharges from the isolation
pond would be needed to dilute out
the nuisance-algae and restore proper
function. The hypotheses were not, of
course, mutually exclusive.
As a compromise, actions suggested
by both hypotheses were taken. First,
hydraulic loading rates to the faculta-
tive ponds feeding the isolation pond
were increased in order to provide more
facultative effluent for fills. Se-
condly, the September and October fac-
ultative overflows were directed into
Pond 4, which had previously been unused,
in order to determine if the absence of
algal sediments would prevent algal
growth during isolation.
Use of the "new" isolation pond did
not restore effective algal removals
or prevent additional algal growth. In
fact, algae thrived in Pond 4, reaching
algal SS and chlorophyll a levels of 94
mg/1 and 1020 Ug/1, respectively.
In November the facultative over-
flows were redirected to Pond 5.
Subsequently, Pond 5 algal density began
a steady decline which continued through
the December isolation cycle. By the end
of January, the algal density had ap-
parently "bottomed out" at 5 mg algal SS
per liter and 10 Vg chlorophyll a per
liter.
Compositions of Effluent Components--
The compositions of major components
of interest in the effluents from the
isolation ponds are given in Table
6.
Volumes—The volumes of effluent in
the June and December overflows were
relatively small, averaging 12,600 cu m.
The June overflow was diminished in
volume by the high evaporation and
percolation rates occurring at that time.
Between 27 June and 23 August, 60,700 cu
m of facultative effluent was discharged
into the isolation pond. This entire
volume of water was lost through evapora-
tion and percolation. A substantial
portion of the November facultative
overflow (58 percent) also disappeared
during its retention in the isolation
pond. The January and February isolation
pond effluents averaged 24,000 cu m. The
113
-------
•y~i x
°s
o ro-
od
H-. a. £ 40
-P" (^3;
—i O
§0
-------
Table 6. Compositions of Woodland isolation pond overflows.
Suspended Solids Chloro-
Drain Volume
Period 3
phyll BODs
Volatile3 a .,
- mg/1
COD
Nitrogen
Total Algal Grazer yg/1
mg/1 mg/1 mg/1
NH3+
mg/1 mg/1 mg/1 mg/1 mg/1 mg/1
April
12-15
1977
May
12-16
1977
June
22-25
1977
Dec.
18-20
1977
Jan.
11-13
1978
Feb.
3-5
1978
42
34
10,500 28
14,800 64
25,300 31
22,700 36
— 13 — 27
— 14 — 47
12 3 114
38 6 281
16 3 100
5 68
78 60
44
77
10 117 68
13 59 46
5 49 35
1.3
0.3
0.4
1.1
0.7
1.1
2.4
3.6
4.1
1.3 5.6
1.2 3.5
1.1 1.8
3.7
3.9
4.5
8.0
5.4
4.0
Algae and grazers separated with 150 ym or 243 ym mesh straining cloth.
NOj and NO^-N not included in Total-N April and May.
substantial rains during January and
February more than offset percolation as
the volume of effluent from the isolation
pond exceeded its influent by 6 percent.
Suspended solids, total suspended
solids—Effluent TSS averaged 39 mg/1
over the report period. The minimum TSS,
28 mg/1, was observed in the June 22-25
effluent while the maximum, 64 mg/1,
occurred in December. Except for Decem-
ber, all effluents contained 42 mg TSS
per liter or less. If December were
excluded, the average effluent TSS would
be 34 mg/1.
It can be seen from Figure 5
that large proportions of the TSS
consisted of ash. The ash content ranged
from a minimum of 31 percent in December
to 69 percent in April and February. On
the average, 52 percent of the effluent
TSS consisted of ash, an unusually high
value relative to the 23 percent ash
content of TSS in Woodland facultative
pond effluents.
__ --The
effluent concentrations of VSS were
substantially lower than the TSS, usually
by a factor of 2. Only in December
did the VSS exceed 20 mg/1.
Beginning with December, the rela-
tive proportions of algal and grazer
biomass comprising the VSS were deter-
mined. Both in December and January
about 85 percent of the VSS consisted of
algal suspended solids (i.e. ash-free
biomass passing through the straining
fabric). This proportion declined
to 45 percent in February. The balance
of the VSS was made up of grazer biomass.
Chlorophyll a--Chlorophyl1 a was
well correlated with algal SS (r2 =
1.0). The minimum concentration observed,
8 yg/1, occurred in the February
discharge while the highest, 281 Mg/1,
was observed in the December discharge.
The average chlorophyll a was 96 yg/1
(59 Vg/1 if December is excluded).
BOI>5—Despite its relatively high
suspended solids content, the December
effluent exerted a 6005 of only 10
mg/1. The average 6005 for December,
January, and February was less than 10
mg/1. The highest 6005 measured in
either isolation pond from offshore
samples was 35 mg/1. This value was
measured on a sample containing a VSS of
103 mg/1. Most samples taken offshore
exerted less than 30 mg BOD5 per
liter.
115
-------
COD—Total (unfiltered) COD ranged
from 117 mg/1 in December to 44 mg/1 in
May. Average total COD was 71 mg/1. The
lowest filtered COD, 35 mg/1, was ob-
served in February. Particulate COD--the
difference between the total and filtered
values—was well correlated with the VSS
(r2 = 0.9). Highest particulate COD,
49 mg/1, occurred in December and the
lowest, 13-14 mg/1, in January and
February.
N itrogen--0n the average about 70
percent of the nitrogen content of
isolation pond effluents was organically
bound. Ammonia and oxidized N made up
the remainder in approximately equal
proportions.
The total N concentration averaged
slightly less than 5 mg/1. The December
discharge contained the most fixed
nitrogen, 8 mg/1. The remaining ef-
fluents had 3.7 to 5.4 mg N per liter.
Algal types—The three algal types
most often found in the effluents
were Oscillatoria, unidentified green
algae, and Chlamydomonas. These algae
were also prevalent in the inflows to the
isolation pond (facultative effluents).
o The greatest algal biovolume, 300
ym x 10° per ml, was observed in Decem-
ber. This consisted mostly of Oscil-
latoria. In January the algal biovolume
was also high, 130 vim 3 x 106 per ml,
and again consisted mostly of Oscil-
latoria. The remaining effluents con-
tained less than 40 um3 x 10" biovolume
per liter with little or no Oscillatoria.
Influence of Wind--
The proportion of ash in the isola-
tion pond effluents was greater than the
approximately 10 percent ash usually
found in algae grown under ideal condi-
tions. It was noticed that samples taken
from the isolation pond on windy days
generally contained fine, greyish mate-
rial which tended to clog the glass-fibre
papers used in determining dry weights.
The ash and volatile components of
suspended solids in daily effluent,
composite samples were roughly correlated
with daily wind movements. On days when
the wind movement was 100 km per day or
64
40
SUSPENDED SOLIDS, mq/jj
—• ro to
0 O 0 0
—
LtbtlMU
ASH ALGAL + ALGAL GRAZER
GRAZER
i
™
TSS
1
—
v i \
I A 1
\
\ \
*>
\
i
>
VSS
1
f
APR MAY JUN v DEC JAN FEB
1977
1978
Figure 5. Total, volatile, algal, and grazer suspended solids in isolation pond
effluents.
116
-------
less, average TSS were 46 percent ash,
whereas in samples taken on days of
greater wind movement, ash made up an
average of 60 percent of the TSS.
Isolation Pond Performance
A summary of the performance of the
isolation pond in terms of removals
of contaminants from facultative over-
flows is given in Table 7.
Isolation Cycle Duration--
The duration of each cycle was taken
as the time'between the start of a fill
and the end of the ensuing discharge. As
noted previously, 2 days were usually
required to fill the isolation pond and 3
to 5 days were needed for its discharge.
On the average, 22 days were allowed for
each cycle.
Hydraulic Loading Rate--
Hydraulic loading rates were cal-
culated by dividing the increase in
pond depth at the beginning of a cycle
(Ad) by the duration of the cycle.
The average loading rate between 28
November and 5 February was 2.6 cm per
day.
Suspended Solids Removal--
The percentage of TSS removed from
facultative overflows was variable.
During the two late spring cycles, the
isolation pond was quite efficient,
withdrawing almost 70 percent of influent
TSS. However, in the January-February
1978 cycle, TSS in the isolation pond
effluent were greater than in the in-
fluent. Overall 35 percent of influent
TSS were removed in the isolation pond.
Chlorophyll a Removal—
Very high proportions of influent
chlorophyll B were removed. As much as
95 percent of the initial chlorophyll a
disappeared over the course of an isola-
tion cycle. The overall removal was 80
percent.
BOD5 Removal—
The average percent BOD5 removed
between 21 December and 5 February
1978 was 61 percent.
COD Removal—
Trends in the proportion of total
COD removed paralleled removals of algal
SS. The poorest removal occurred in the
November-December cycle at the same time
that the proportion of algal SS removed
was at a minimum. The greatest removal
was observed in April-May when the
removal of algal biomass was also at its
maximum. The overall percentage of total
COD removed was 46 percent.
Total Nitrogen Removal--
The trends in nitrogen removal were
similar to those in algal SS and total
COD removal. The maximum value for
nitrogen disappearance, 73 percent,
Table 7. Performance of the Woodland isolation pond.
Hydraulic Removals from Facultative Pond Overflows, 70
Period Duration Loading 0 , , _ , _ . ,
Dav? RafP Suspended Chloro- Total
0373 J^L Solids phyll BOD. COD Nitro-
April 18
- May 16 28
1977
June 6
- June 25 19
1977
Nov. 28
- Dec. 20 22
1977
Dec. 21
- Jan. 13 23
1978
Jan. 17
-Feb. 5 19
1978
Average 22
Total Algae a J Total Filtered gen
69 85 95 -- 77 -- 73
67 82 83 -- 59 -- 42
3.3 9 33 54 -- 13 — 19
1.8 45 65 78 50 52 34 37
2.7 <13> 71 92 72 31 10 18
2.6 35 67 80 61 46 22 38
117
-------
was achieved between April and May while
the smallest, 19 percent, occurred
from November to December. The average
nitrogen removal was 38 percent.
Discussion
The overall performance of the
Woodland facultative/isolation ponding
system is presented in Table 8. On a
seasonal basis, the facultative ponds
were consistent in their ability to
remove significant proportions of COD,
8005, and nitrogen from the influent
sewage. The high rate of nitrogen
subtraction, 70 percent, is particularly
noteworthy as the removal of nitro-
gen in conventional sewage treatment
plants can be accomplished only with
additional equipment. The 6005 removal
achieved in the facultative ponds,
87 percent, was marginally satisfactory
with respect to EPA standards.
The level of treatment was consider-
ably improved by the isolation pond. An
overall BOD^ removal of 96 percent was
achieved between October and December.
The extent of nitrogen removal was
increased to 83 percent. The COD removal
rate, which was 68 percent in the facul-
tative ponds, was increased to 79 per-
cent. Suspended solids of sewage origin
were, of course, practically 100 percent
removed. The proportion of ash in the
isolation pond effluents was greater than
normally observed in algal pond ef-
fluents. Higher ash contents were
associated with high wind velocity as
Table 8. Overall performance of Woodland
ponding system.
Removals From Raw Sewage, "L
Period Facultative Facultative &
Ponds Isolation Ponds
Total
Total
COD BODc Nitro- COD BOD5 Nitro-
gen gen
April-
June 67
1977
July-
Sept. -- 87
1977
Oct.-
Dec. 69 88
1977
73 87
68 a a
70 71 96
89
a
78
Ave. 68 87 70 79 96 83
aNo overflows from isolation pond
during this period.
previously mentioned. This is shown in
Figure 6 where the ash and volatile
components of suspended solids in isola-
tion pond effluents are compared to
daily wind movements. On days when
the wind movement was 100 km per day or
less the average TSS was 46 percent ash
whereas in samples taken on days of
greater wind movement ash made up an
average 60 percent of the TSS.
An explanation of the a-sh fraction
is complex. A first assumption was
resuspension of bottom sediments by wind
since the higher ash contents were
associated with high wind velocity. To
check the bottom sediment resuspen-
sion hypothesis, a wave study was made.
Observations of the "isol at ion pond
during windy days indicated that waves
commonly reached 10 cm in height with
lengths of about 50 cm and periods on the
order of one second. When the ratio of
basin depth to wave length is greater
than one-half, waves behave as if they
were in deep water. The isolation pond
is about 150 cm deep when full, thus
yielding a ratio h:L of 1.5. Horizontal
velocity of water at the pond bottom,
moving in response to waves of the size
given above, was calculated by the method
of Williams (14).
Substituting in the .typical dimen-
sions of Woodland's waves resulted
in the Williams formula in a predicted
velocity of 4 x 10-7 cm/sec. This
result is much lower than the critical
scour velocity of 3 cm/sec calculated
from the equation of Camp (15) to be
required to. resuspend organic sediments.
On the basis of these calculations, it
appears that bottom sediment resuspension
alone is not responsible for the higher
ash content observed on windy days.
An alternative explanation which
apparently fits the observed facts
is that, due to localized high pH, marl
may form in close association with
or absorbed to the Oscillatoria cells and
remain attached to the filament sur-
face. Marl normally consists of a high
fraction of calcium carbonate but also
may contain aluminates and silicates.
During windy periods, those Oscillatoria
nearest the surface and therefore richer
in ash become dispersed throughout the
hypolimnion and a higher ash suspended
solids would be obtained.
A third explanation is that during
windy periods, bank erosion occurs
and, due to circulation, fine clay
becomes mixed into the hypolimnion.
Studies are underway to determine if the
ash. contains a high percentage of cal-
cium carbonate, but results thus far are
inconclusive. There is, of course, the
possibility that all of these phenomena
118
-------
APR
Figure 6. The influence of wind on the ash content of suspended solids in isolation
pond effluents.
contribute to the observed- high ash
content.
The algal species important in the
isolation ponds were for the most part
the same species present in facultative
effluents. In one notable exception,
Closterium, a genus rarely observed in
the facultative ponds, grew up in (iso-
lation) Pond 5 to a concentration about
twice that present initially. However,
it disappeared within about a month.
The algal genus responsible for most
of the 5-month long upset of the pond
isolation process was Oscillatoria, which
was also predominant in one of the
facultative ponds. It is not understood
at this time how these algae were able to
grow to such high densities when ammonia-
nitrogen concentrations had fallen below
0.5 mg/1. One possible explanation is
that the release of nitrogen from pond
sediments was sustaining the (3;5c_i_l-
_1 £» t o_r j. a). This possibility, however,
conflicts with the observation that use
of a previously empty pond for the iso-
lation phase of treatment did not result
in a decrease in algal concentration.
There is also the possibility that
the Oscillatoria was able to anaerobical-
ly fix nitrogen from the atmosphere to
satisfy its requirements. However, we
were not successful in inducing N2 fixa-
tion in samples of 0_£c_iJL_lcitjo_r ijj taken
from Woodland under conditions which did
allow Plectonema, another non-
heterocystis blue-green alga, to exhibit
fixation.
One factor which does indicate the
effectiveness of pond isolation in re-
moving algae is the chlorophyll a concen-
tration. Algae are normally about 1
percent chlorophyll a and reference to
Table 6 indicates that the maximum
chlorophyll a concentration--281 (micro-
grams per liter)—corresponds to an
algal concentration of 28.1 mg/1.
INTEGRATED PONDING
Integrated ponding using the phase
isolation concept involves optimum
designs for the attainment of the most
complete treatment possible in ponds.
Ideally, the systems use continuous flow
119
-------
growth ponds in series, separation
ponds which are either operated in series
or parallel, continuously or in a
batch. One example of an integrated
ponding system presently functioning
is in St. Helena, California. This
system consists of a 2-acre facultative
pond, a 5-acre high-rate pond, a 2-acre
algal sedimentation pond, and two
5-acre maturation groundwater recharge
ponds. We discuss here primarily
those aspects which contribute to the
algal separation.
Sedimentation, grit, and grease
removal, together with methane fermenta-
tion and some biochemical oxidation,
occur in the primary facultative pond of
a series. This primary pond should be
designed to permit thermal stratifica-
tion to occur and to provide an anaerobic
volume in which methane fermentation can
occur with no intrusion of oxygenated
surface waters. In such an environment,
both methane fermentation and nitrate
reduction occur. The primary pond
processes of methane fermentation and
nutrient reduction apparently greatly
enhance the ultimate settleability of
microalgae in the separation ponds
because they contribute to diminishing
the quantity of carbon and nitrogen
available to the algae. Fine silt and
other inert materials are also removed by
sedimentation and autoflocculation in
facultative ponds with the result that
wastes entering the high-rate pond are
freed of these materials and, hence, a
greater fraction of the available light
penetrates into the water and is avail-
able to the algae. As has been discussed
before (**) , photosynthetic oxygenation
and biological oxidation occur most
effectively in shallow, mixed ponds,
secondary to facultative ponds in the
series. Ideally, in a shallow, mixed
pond, algae grow Up to their full light-
limited potential, absorbing most of the
remaining carbon dioxide and ammonia from
the water, greatly enhancing their
tendency to settle. An important influ-
ence of algal growth in the high-rate
pond on separation is that they decrease
the total alkalinity and diminish bi-
carbonate concentrations with respect to
carbonate, therefore increasing the pH.
This, in turn, tends to enhance formation
of precipitates which aid in improving
the settleabi1ity of the algae and,
coincidentally, of the bacterial cells in
the system. The higher pH levels and
somewhat higher water temperatures
induced by algae tend to decrease the
solubility of waste components including
calcium and magnesium salts, and also
tend to precipitate heavy metals. Thus,
some reduction in TDS and heavy metal
content may be observed (particularly
where evaporation is not high). The
mixing characteristics of the high-rate
ponding process improves the settle-
ability of flocculent materials apparent-
ly by increasing floe size through
particle entrapment and, perhaps, by
other mechanisms. A second influence of
algae in the high-rate pond is the
removal of ammonium in direct proportion
to their growth. Two factors are actual-
ly involved here—loss of ammonia to the
atmosphere and uptake of ammonium by
the algae. Ammonia loss to the air is
enhanced by the mixing and is increased
as the water temperature and pH increase.
Algal growth brings about the high pH
and, inasmuch as algae convert light to
heat with high efficiency, also brings
about a higher temperature in the water.
The ammonium taken up by algae usually
amounts to about 8 percent of their dry
volatile solids.
The net result is that the high-rate
pond either alone or in series with a
preceding facultative pond or primary
treatment system improves the settle-
ability and, hence, the harvestability of
microalgae in the system.
Detailed results of the separation
of algae obtained in the high-rate pond-
ing process have been published elsewhere
and can be summarized as follows: In
studies by Oswald and Romani (16), a
facultative pond, followed by a high-rate
pond and a covered sedimentation pond,
gave more than 90 percent suspended
solids removal in the settling pond.
Work in the Philippines in 1977 (17),
using screened raw sewage introduced to
high-rate ponds followed by a settling
pond, gave results indicating a minimum
75 percent suspended solids removal in
the settling pond. In those studies, no
facultative pond was used because the
sewage available for the study was low in
both BOD and nitrogen. On-going experi-
ments at our laboratory with pilot
high-rate ponds have demonstrated that
over 70 percent of the algae could be
removed by a continuous settling chamber
operated at a detention time of only
12 hours. Our conclusion, therefore, is
that with proper design and under
favorable environmental conditions,
either primary treatment or a facultative
pond preceding a high-rate pond, followed
by a short detention time settling
pond will result in removal of 70 percent
or more of the suspended algae in
the high-rate pond effluent without
chemical additives or special mechanical
manipulation. The key is apparently the
combination of carbon uptake, nitro-
gen loss, and mixing applied in the
high-rate pond.
120
-------
MICROSTRAINING FOR
ALGAL REMOVAL
We have recently reported extensive
work on the use of miorostrainers
for algal separation (18). Although
stainless steel microstrainers used
in the past for algal separation have
been subject to fouling and corrosion
(19), the recent development of non-
fouling, non-corroding plastic screens
shows considerable promise. Our current
information is that such screens have a
life expectancy of at least 2 years since
several of our experimental units are of
that age and still functional. Plastic
screens, having apertures as small as 20
microns, are now available with through-
puts of about 2 gallons per sq ft per
minute. Throughput is, of course, propor-
tional to aperture size and about 20
gallons per sq ft per minute will pass
through a 50 micron rotary screen. The
cost of microstraining at the 26 micron
level has been estimated at about $50
(1977) per million gallons of liquid
processed including the equipment
interest, operations and maintenance, and
all other cost factors. Microstraining
costs decline somewhat with plant size,
but the major item of cost is the strain-
ing surface itself which depends on
throughput rates, mesh and particle size
and concentration.
The key parameters in the effective
operation of microscreens for algae re-
moval from pond effluents is particle
size distribution and concentrations.
Particle sizes depend on the algal
species that populate the ponds, their
colonial aggregations and flocculation
behavior. Obviously for microstraining
to be effective, the algal cells, colo-
nies or floes must be significantly
larger than the screen size. A relative-
ly high concentration also helps algae
removal as it results in formation of a
"precoat" that helps to trap materials
which are smaller than would normally be
retained, allowing a greater variation in
particle size distribution. High-rate
pond systems allow both achievement of
relatively high algal concentrations and
some control over the algae population
which could be used to selectively culti-
vate larger, filamentous or colonial.
algae types readily removed by
microstrainers.
Extensive experiments were carried
out to test this concept using experi-
mental, 12 n)2, high-rate ponds. The
principal variables tested were detention
times, specific biomass recycle, mixing
speeds, and inoculation with desired
algae types. The results demonstrated
that it was feasible to maintain for
considerable periods of time algal
populations consisting of colonial
and Scenedesmus which could
be efficiently (75 percent-95 percent)
removed by microstrainers. However,
after a few weeks to months upsets in
the algal populations (e.g. change of
species, grazing by zooplankton) led to a
deterioration of effluent quality. Also,
the pond operations that resulted in
algal populations exhibiting good harvest-
ability also resulted in poor algal
biomass productivities. Thus, this
approach to algal removal still requires
further R & D and can presently be
considered only in combination with other
processes such as pond isolation or
algal flocculation.
CONCLUSIONS
The investigation of pond isolation
at Woodland suffered from a number
of difficulties as is to be expected when
a new process is tested on a large scale
for the first time. Chief among these
problems were lack of control over
facultative pond loadings, wind-induced
silt resuspension and absence of dis-
charge during critical summer months. In
spite of these problems it was shown that
use of a draw-and-fill operated secondary
(isolation) pond can allow significant
removals of algae from facultative pond
effluents. Possible upsets to the
process by blue-green algae such as
O^lIl-StpJIii* need to be investigated
further. It may be possible to limit
the growth of these algae by increasing
the loading to the facultative ponds
during critical summer months.
Integrated ponding, where a shallow
mixed, high-rate pond is used to produce
settleable algal biomass which is sub-
sequently removed in a deep, quiescent
pond, requires a greater degree of
operator attention than the facultative-
isolation system. However, it becomes
preferable in areas of higher population
density because of its more efficient use
of land.
In spite of high algae removal
efficiencies, both systems appear to
require a final polishing step to enable
them to meet effluent standards more
stringent than the general 30/30 EPA
requirement. This step could take
the form of natural gravel beds such as
are used at Santee, California. Alter-
nately, the process of intermittent sand
filtration could be used. This method is
particularly compatible with pond iso-
lation because the effluent is drawn once
every 20 days thus allowing a resting
period for the filter. The entire filter
could be flooded thus simplifying the
distribution network required. Also, the
length of filter runs could be extended
because the bulk of organic matter
121
-------
(algae) would have been removed before
reaching the filters. Some type of rapid
sand filtration would be more suited for
polishing effluents of integrated ponds, 8.
both to conserve land and because the
flows are continuous.
The low operations and maintenance
costs for ponds and the opportunity
for energy conservation they allow 9.
relative to conventional, mechanical
systems make these systems attractive
wherever favorable climatic conditions
exist. Present discharge standards,
however, tend to discourage their
application. In particular, pond systems
and other aquatic plant based wastewater
treatment systems should be subjected to
discharge requirements which, without
lowering overall pollution standards, 10.
take cognizance of the variations in
performance standards that result due to
seasonal and other climatic changes.
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18(3):433-458, 1946.
2. Oswald, W. J. , and H. B. Gotaas.
Photosynthesis in Sewage Treatment.
Proceedings American Society of
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1955.
Gloyna, E. F., and E. R. Hermann.
Some Design Considerations for
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Proceedings of the American Society
of Civil Engineers, 82(SA4), Paper
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Oswald, W. J. Syllabus on Waste
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Sanitary Engineering Research
Laboratory, University of California,
Berkeley, 1976.
Oswald, W. J., and C. G. Golueke.
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by Phase Isolation. First Annual
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Oswald, W. J. Method of Waste
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United States Patent 4,005,546,
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University
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13.
14.
15.
Oswald, W. J. Experiences with 17.
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Reynolds, J. H., et al. Performance
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Research Laboratory, Utah State
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1977.
Raymond, Vail and Associates,
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Dildine, E.D., and J.R. Franzmathes.
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Administration, Kansas City, p.
194-200, 1970.
Oswald, W. J. The Engineering
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West Palm Beach,. Fla., 1978.
Williams, J. The Classical Approach
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18. Benemann, J. R., et al. Species
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ACKNOWLEDGMENT
We are indebted to Mr. Al Hiatt,
Director of Public Works for the City
of Woodland for supporting portions of
this study. Appreciation is also
expressed to Mr. Rob Thomson and Mr.
Randy Yackzan of the University of
California, Sanitary Engineering Research
Laboratory; their cooperation has
greatly facilitated our work.
123
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AN INTEGRATED, CONTROLLED ENVIRONMENT AQUACULTURE LAGOON PROCESS
FOR SECONDARY OR ADVANCED WASTEWATER TREATMENT
S. A. Serfling and C. Alsten*
INTRODUCTION
Conventional wastewater treatment
lagoons have been limited in their
application because of the high BOD and
suspended solids which remain in the
effluent in the form of algae, and
their extensive land requirements. In an
attempt to provide more process control
and greatly reduce the land area require-
ments, engineers have developed a variety
of relatively high technology treatment
processes such as activated sludge,
trickling filters, bio-disc, and elabor-
ate advanced wastewater treatment pro-
cesses. It is now becoming clear that
these high technology solutions are
not only failing in many cases to meet
design or discharge standards but they
are also very expensive to construct
and operate, particularly in terms of
energy consumption (EPA Report to
Congress, 1975-76; Engineering News
Record, 1978).
Both the conventional lagoon and the
higher technology treatment processes
have been designed for the purpose of
sewage stabilization and disposal into
the aquatic ecosystem. With increasing
population densities, it is becoming
obvious that what might appear to be a
satisfactory disposal solution for
one community becomes an environmental
degradation problem for its neighbors.
This problem, together with the in-
creasing need for water and fertilizer,
leads to the inescapable conclusion that
wastewater must be dealt with as a
resource to be managed rather than a
problem to be disposed of. Taking this
perspective then, wastewater treatment
processes for the future must be designed
*S. A. Serfling is President of
Solar AquaSystems, Inc., Encinitas,
California; and Director of Aquaculture
for the Applied Aquatic Resources In-
stitute, with offices in the Presidio of
San Francisco, and Encinitas, California.
C. Alsten is a Research Associate with
AARI and Solar AquaSystems.
to operate as managed ecosystems with
controlled harvesting of nutrients, and
planned reuse of the water either direct-
ly or indirectly by "downstream" eco-
systems or communities.
It is, therefore, encouraging that
the 1977 Clean Water Act requires that
agricultural, aquacultural, and silvi-
cultural alternatives for wastewater
reuse be evaluated and encouraged as
treatment mechanisms. The purpose of
this paper is to present information
on a managed ecosystem type lagoon system
utilizing an integrated controlled
environment aquaculture system for
achieving secondary or advanced tertiary
quality effluent.
Definition of Aquaculture
Treatment Systems
Aquaculture, similar to agriculture,
has typically referred to the farming
of aquatic foods for direct or indirect
human consumption (Bardach, Ryther
and McLarney, 1972). By this definition
then, wastewater would merely be a
source of nutrient input, similar to
animal manures, agricultural waste
products or inorganic fertilizers.
Although this is a common practice in
developing countries (which often export
the harvested fish or shellfish to the
United States), this is not the type of
aquaculture wastewater treatment ad-
dressed in this paper. Wastewater must
first be "treated," and reuse of by-
products is an optional activity of
secondary concern. We propose as a
preferred definition of aquaculture
wastewater treatment (AQWT), a process in
which aquatic species are intentionally
stocked and harvested as part of a
managed ecosystem for the purpose of
removing wastewater nutrients and/or
pollutants. The harvested by-products
may or may not be used for any direct
human benefit, such as organic compost,
fertilizers, methane gas, methanol, or
animal feeds (see Figure 1), but they are
not intended for direct human consump-
tion.
124
-------
In a broad sense, all biological
treatment processes could be considered
aquaculture, since even the activated
sludge process is entirely dependent
on the growth, productivity, survival
and harvesting of microorganisms for its
treatment effectiveness. But due to
the lack of intentional stocking or
harvesting of organisms for an intended
beneficial reuse, activated sludge does
not fit the definition of aquaculture
wastewater treatment. For similar
reasons, algal lagoons which utilize
mechanisms such as chemical precipitation
to "harvest" the algae and return it to
the pond for further degradation and
stabilization, are not considered aqua-
culture. The distinction between the
various means of aquaculture as it
related to wastewater treatment has
been well discussed by Duffer and Moyer
(1978).
Limitations of Conventional
Wastewater Treatment Lagoons
Wastewater stabilization or oxida-
tion lagoons have proven successful in
stabilizing wastewater by means of
natural biological processes with low
energy and maintenance requirements. In
contrast to managed ecosystem processes,
the objective of wastewater treatment
lagoons has been the stabilization,
rather than the permanent conversion and
removal of the wastewater pollutants
and nutrients. The design features of
wastewater lagoons are thoroughly dis-
cussed by Oswald (1963) and Gloyna
(1971). Unfortunately, the requirement
for long retention times (typically
80-150 days) with large land areas, and
the inability to achieve secondary or
higher quality effluent on a reliable
basis has restricted the application of
wastewater stabilization lagoons.
Both problems, large land area
requirements and poor effluent quality,
are caused primarily by the dependence
of the lagoon process on single cell
algae. The biological concepts which
describe the functioning of wastewater
treatment lagoons has been thoroughly
reviewed by McKinney (1974), in which
he describes the cyclical and revers-
CONVERSION OF WASTEWATER TO VALUABLE BY-PRODUCTS
THROUGH AQUACULTURE
Raw
Qf " ™~ a~
Primary
•— ^^— — »Bacterii
Wastewater
Solar
AquaCell '—•Aquatic
System
Purifiec
a.rv~*.i*..~. r-*-*-i*hrnrr":..
Plants-
Water—
-Anaerobic Digestion—-
-Groundwater Recharge-
.Methane 6
Electricity -~— -
_>.Fish b&>
^Shrimp ^SW^S~
* Methanex^^ . ( „ A ^+*~~
^•Electricity w J=£*^
itniHliMInnraM'
Golf Courses
Fishing, Boating «a**^>
— — * Industrial Water «S!»St^^fc
_M» Maintenance of wivS^sfcidSvw
Water Table W
-------
ible nature of the synthesis and en-
dogenous respiration processes occurring
with the algae, and aerobic and an-
aerobic bacteria communities within
the pond. Under proper conditions
algae can be highly productive, and
rapidly assimilate and convert waste-
water nutrients into a more publicly
acceptable form, while producing oxygen
in the process. However, the reverse
cycle can just as easily and quickly
take place. Under fluctuating conditions
of solar input, temperature, nutrient
loading, and concentrations of toxic
substances, the algae die, decay and
release the nutrients back to the water.
Because of the inherent instability of
algae, wastewater can be stabilized with
an algal pond system only after long
retention time (for example, see Middle-
brooks et al., 1974). Recognizing the
need for a managed ecosystem approach,
McKinney (1974) concluded "the key to
successful production of quality ef-
fluents from oxidation ponds lies in
algae removal."
To take advantage of the rapid
growth and oxygen producing features of
algae, Oswald (1973) developed an ac-
celerated algae culture system. This
managed process utilized anaerobic
primary treatment, shallow algae culture
ponds to maximize sunlight penetration,
long narrow channels to minimize short-
circuiting, pre-inoculation of algae to
quickly initiate the photosythe tic
process, and various harvest mechanisms
to remove the algae after only 2-4 days
retention time. The controlled process
reportedly works well, except for the
difficulties encountered in attempting to
reliably and inexpensively harvest
the microscopic algae cells. Numerous
other researchers have also encountered
technical or economic limitations with
micro-screening, chemical coagulation,
centrifugation, sand filtration, or pond
isolation techniques for removing algae
(for example, see Benemann et al.,
1977).
Because of the widely fluctuating
performance of algae based ecosystems,
particularly under conditions of season-
al changes and climatic differences
in different geographic zones, engineers
have experienced difficulty in develop-
ing or utilizing reliable mathematical
models for the design of algae lagoon
systems. Other engineers have greatly
reduced the land requirement for waste-
water treatment by utilizing expensive,
high technology processes such as acti-
vated sludge, trickling filters, and
bio-disc processes to obtain better
control under high loading rate, short
retention time conditions. Yet, process
instability and poor effluent quality
still remain a problem (EPA Report
to Congress, 1975-76, and Engineering
News Record, 1978). Once again, the
problem is due primarily to the instabil-
ity of unicellular type organisms, (in
this case, bacteria and protozoa) as the
sole biological component for treatment.
Aerated lagoons have been developed
to provide a good compromise between the
low technology stabilization lagoons and
the higher technology activated sludge,
trickling filter or bio-disc processes.
The assurance of constant oxygen levels
allows much higher loading rates without
process breakdown or odor problems, but
the effluent quality from most aerated
lagoons still fails to meet EPA discharge
criteria because of the high quantity of
algae cells remaining in the effluent.
UPGRADING LAGOONS USING FLOATING
AQUATIC MACROPHYTES
Advantages of Floating
Maerophytes
Floating aquatic macrophytic plants
such as water hyacinths (^i^_hho_r_ ji ji ja
crassipes) or duckweeds (Lemna spp., or
§£i.L°.i§.l.a. J.EE • ) offer the following
advantages over suspended algae for
treating wastewater:
1) Stabi1ity and Hardiness: Ex-
tensive studies by Wolverton (1978) with
water hyacinths, and Hillman and Culley
(1978) and Harvey and Fox (1973) with
duckweeds have demonstrated that both
plants are very stable and hardy organ-
isms that can survive and rapidly multi-
ply under varying environmental condi-
tions. In fact, the plants have been
shown to greatly increase both average
and total productivity when cultured in
wastewater treatment ponds. They can
tolerate widely fluctuating nutrient
loading rates, solar input, water and air
temperature changes, fluctuations in
water chemistry such as pH, carbon
dioxide, alkalinity, and are not affected
by toxic compounds (heavy metals, chlor-
inated hydrocarbons, etc.) at concentra-
tions typical in most municipal sewages.
Studies by Wolverton (1978) have shown
that water hyacinths can be used for
concentration, removal, and potential
recycling of a variety of heavy metals
occurring in many industrial effluents.
A good review on the use of aquatic
plants for wastewater treatment is
provided by Duffer and Moyer (1978).
2) Provide Shade to Prevent Algae
Growth: Floating aquatic macrophytes
eliminate high effluent levels of sus-
pended solids and BOD caused by algae
cells because the sunlight penetrating
through the plant fronds is insufficient
in most situations to allow significant
phytoplankton growth. For this reason,
126
-------
aquatic macrophytes are showing good
potential as "polishing" ponds to be
added on to conventional treatment
lagoons or higher technology processes
(Cornwell et al., 1977) .
3) Rapid Growth,
High Productivity:
Water hyacinths and duckweeds have
been shown by numerous researchers to be
extremely fast-growing and, thus, have
the capability for removing large quan-
tities of sewage nutrients in a rela-
tively short time and small land area.
It is a relatively simple concept that
in order to clean wastewater, one must
remove from it the chemicals originally
put into the water during its use, and
the quantity removed must correspond
more or less to the quality of effluent
desired. Thus, the productivity of
the cultured biomass bears a direct
relation to the ability of the system
to purify water.
4) I±jLl£_°..£_iLa-.Ly_.e_jL Ji: The large
size of the floating aquatic macrophytes
makes their removal relatively easy
in comparison to unicellular algae.
Water hyacinths do present a difficult
harvest situation if they have been
allowed to grow uncontrolled for many
months, resulting in heavily intertwined
plants which resist removal. Harvesting
on a regular schedule reduces this
problem significantly. Duckweeds
are much easier to harvest because of
their smaller size and absence of en-
tangling roots or stolons. They can be
removed by simple surface skimming
devices as part of the pond overflow
mechanism.
5) High
hyacinths
Reuse Potential: Water
and duckweeds offer numerous
reuse possibilities, including high
protein animal feeds, conversion to
rich organic compost or fertilizer,
conversion to methane gas, or methanol.
Water hyacinths grown in sewage lagoons
typically average 20 percent protein
(Wolverton et al., 1978), while duck-
weeds have been shown to average over
40 percent protein (Hillman and Culley,
1978). Studies by Wolverton (1978) and
Lecuyer and Marten (1975) have demon-
strated that one acre of water hyacinths
can produce an average of 200,000 to
300,000 cubic feet of methane gas per
year. Tables 1 and 2 summarize the
yields and quantities of aquatic plants
Table 1. Comparison of solids production for aquatic macrophyte vs. conventional
systems.
Ave. Quantity Per Million Gallons
1.
2.
3.
4.
5.
6.
7 '„
8.
9.
Imhoff Tank
(Primary)
Primary Sedimentation
(Undigested)
Activated Sludge
(Secondary, undigested)
Activated Sludge & Primary
(Anaerobically digested)
Chemical Precipitation
(De-watered-vacuum filter)
Water Hyacinths
(AquaCell lagoon, 1 acre/mgd
@ 40 dry ton/acre/year)
Duckweeds
(AquaCell lagoon, 2 acres /ragd)
Algae Lagoon
(50-100 day retention time)
High Rate Algal Lagoon
(2-3 days retention time)
Wet
Weight
(Ibs)
25.000
150.000
7.000
12,000
4,400
1,600
416-
3,333
4,400-
6,000
Dry
Weight
(Ibs)
690
1,250
2,250
1,400
3,300
220
80
20-
166
220-
300
Cubic
Ft.
67
390
2,580
360
193
160
(chopped)
100
(compost)
26
7-
52
68-
93
%
Moisture
85
95
98.5
94
72.5
95
95
95
95
Note: Data on
1-5. From W.P.C.F. (1977).
6. After Wolverton et al.
7. Myers (1977) .
8. Metcalf and Eddy, Inc.
9. Benemann et al . (1977).
(1975) and Lecuyer
et al.
(1972) and Benemann et al .
(1975).
. (1977)
127
-------
and their conversion products that
are obtainable under various wastewater
treatment conditions.
6 ) AcWja ri £^e cI_T e_£_t !.ajli_Q.ii a.!! t-i
Effluent Can Be Economically Achieved :
Due to the stability, high productivity,
shading effect, and relatively easy
harvest, floating aquatic macrophytes can
produce advanced tertiary quality water
with little capital or operating costs.
The plants convert dissolved nutrients
into a fixed biomass which is stable
until harvested, and does not recycle or
remain in the effluent or pond bottom to
create problems at a later time. This
controlled aquaculture process does not
require the expensive energy, chemicals,
construction or maintenance cost that is
typically utilized as a form of "brute
force" treatment by conventional high
technology advanced wastewater treatment
systems.
Disadvantages of Aquatic
Macrophytes
In spite of the numerous advantages
of aquatic macrophytes, several dis-
advantages exist which have limited their
usefulness to date. Water hyacinths are
extremely hardy under warm, humid condi-
tions, but because of their tropical
nature, cannot survive cooler winter
temperatures during which wastewater
treatment must still be achieved.
Table 2. Production quantities of aquatic plants and their conversion products.
Quantity of Harvest
Per Acre (Wet)h
Converted Converted
to Compost to Methane
(80% H20 Loss) Gas
Weight
lbs/ac/
day
Volume
Whole
ft3/ac/
day
Chopped
ft3/ac/
day
Dry
Weight
lbs/ac/
day
Volume
yd3/ac/
day
Weight
lbs/ac/
day
Volume
ft3/ac/
day
1) Water Hyacinth5
Density^
% Moisture
2) Duckweeds0
- Summer
- Winter
Average Daily
Production
Density
957,
1,095
550
850
5-15 30-50
lbs/ft3 lbs/ft3
95% 95%
18
9
14
60
lbs/ft3
e
lbs/ft3
-0- 67% -0- -0-
54 0.48 273 325f
27 0.25 135 162
42 0.37 197 252
20
lbs/ft3
g
Notes:
Based on a composite of data from Wolverton (1978); Ryther et al. (1978);
and A.A.R.I. (1978).
bAfter Bagnall (1975).
cBased on a mixed culture of duckweeds, after Myers (1977) .
dAfter Wolverton et al. (1975); Lecuyer et al. (1975).
eEmperical measurement (A.A.R.I.).
Estimated 6 ft /lb dry duckweed.
"Estimated.
These production figures are for water hyacinths alone or duckweek alone
and are not additive in combined culture.
128
-------
Even in southern climates such as Missis-
sippi and Texas, water hyacinths die back
during the winter and lagoon treatment
efficiency suffers (Wolverton, 1978;
Dinges, 1978). In many locations water
hyacinths are considered a noxious
weed, and any environmental concerns must
be evaluated before their use.
In contrast, duckweeds are well
known for their ability to survive and
grow in cold climates, and there are
numerous species known throughout the
world in all climate zones. Duckweeds
are limited by two main problems: they
are highly prized as food by most fish
and waterfowl, and can be quickly
consumed in any open pond; and they
are easily blown by winds upon the pond
shore. Consequently, duckweeds are
not reliable as a treatment method unless
provision is made to eliminate predators
and construct long narrow ponds with high
banks or wind screens to prevent surface
disruption, as suggested by Hillman and
Culley (1978).
Evaporation losses from macrophytic
plants can also be a serious problem in
areas with a shortage of water. Del
Fosse (1977) in reviewing literature on
water hyacinth culture, states that
researchers have shown water hyacinths
increase evapotranspiration water losses
by as much as 2 to 7 times normal rates,
or the equivalent of 3 to 12 acre feet
every six months. Because of the prob-
lems encountered with low winter tempera-
tures, predators, wind effects, and
evapotranspiration, all of the chief
researchers on floating macrophyte plants
have stated that greenhouse pond covers
would be desirable and perhaps essential
in order to allow macrophyte systems to
be more adaptable to different environ-
mental conditions (Wolverton et al. ,
1978; Dinges, 1978).
ADVANTAGES OF THE SOLAR AQUACELL
CONTROLLED ENVIRONMENT PROCESS
The integrated, controlled environ-
ment aquaculture treatment system de-
scribed in this report is the outgrowth
of a five-year research development
program which has concentrated on the
integration of five different but rela-
tively well-proven technologies. ' These
technologies have been incorporated into
what is known as the Solar AquaCell
Process in order-^ta overcome the above-
mentioned problems and combine the best
features of low construction and oper-
ating costs of aerated lagoons, with the
process control, advanced treatment
capability, and reduced land requirements
of conventional high technology treatment
processes. The intention was to develop
a more reliable, shorter retention time
lagoon process that could extend the
applicability of lagoon systems to
communities otherwise forced to construct
expensive and energy intensive, high
technology systems.
The five main technologies inte-
grated into the system (Figures 2 and 3)
are: 1) The basic multicell lagoon
process; 2) the use of floating aquatic
macrophytes, particularly water hyacinths
and duckweeds in combination; 3) green-
house covered ponds to provide insulation
and transfer of solar heat to the water;
4) high surface area fixed-film sub-
strates (Activated Bio-Web Substrates) to
provide habitat for the bio-film and
associated microorganisms and inverte-
brate detritivore community; 5) a dual
aeration and solar heat exchange system
for maintaining proper dissolved oxygen
concentrations, transferring solar heat
from the air phase to the water phase in
order to increase metabolic rates and
treatment efficiencies, and providing for
a gentle stirring and partial mixing of
the wastewater past the aquatic plant
surface area and the bio-film substrates.
Historical Development
of the System
Development of the Solar AquaCell
process began in 1972 using the five
basic elements of the system for treating
and recycling wastewater from intensive
aquaculture food production systems
designed for producing freshwater fish
and shrimp. Commercial fish feeds, and
cattle and chicken manures were used as
the nutrient input to tanks containing
high surface area plastic substrates,
floating aquatic macrophytes, diffused
aeration, and greenhouse covers. A
variety of microorganisms, protozoa and
invertebrate detritivores (amphipods,
ostracods and snails) were added to the
system to recycle particulate wastes back
to the fish and shrimp. The organic
input and waste production load added to
the system each day was qualitatively and
quantitatively very similar to domestic
sewage except for phosphates, which are
much higher in sewage due to the use of
household detergents.
Studies conducted with these systems
over a three-year period demonstrated
that the integrated process was highly
sta.ble, and that essentially all of
fhe waste products and nutrient input
could be completely recycled through
food chain processes to be harvested in
the form of fish, shrimp, and aquatic
macrophytes. It was a particularly
interesting observation that the bac-
teria/detritus/detritivore food chain
pathway was considerably more efficient
at converting and recycling nutrients
than was the photosynthetic plant path-
129
-------
way. Studies of nitrogen flow within the
system indicated approximately 75 percent
was recycled through the bio-film/detri-
tus/detritivore pathway under optimal
harvest conditions by the floating
aquatic macrophytes (Serfling, 1976).
Under these intensive culture conditions,
BOD and suspended solids were typically
maintained at levels below 20 parts per
million, while ammonia and nitrite
were less than 0.1, and total nitrogen
less than 15 parts per million. The
greenhouse tank covers functioned well
during the colder winter periods and
allowed continued growth of the aquatic
macrophytes and other food chain organ-
UPGRADING TREATMENT LAGOONS USING CONTROLLED ENVIRONMENT AQUACULTURE
OXIDATION LAGOON
- Poor reliability
- High algae, BOD, S.S.,
odors.
- High land area
(60-120 acres/MGD)
AERATION LAGOON
- Improved process
stability with higher
loading rates.
- Reduced land area
(15-30 acres/MGD)
FLOATING PLANTS ADDED
- Eliminates algae
- Reduces BOD, S.S.
- Limited to warmer
climates.
- 15-30 acres/MGD
BACTERIAL & INVERTEBRATE
SURFACE AREA ADDED
- Increased rate of
nutrient conversion,
BOD, S.S. reduction.
- Improved process
stability.
- Reduced land area
(5-10 acres/MGD)
SOLAR POND COVER ADDED
- Improved winter operating
temperature.
- Reduced land area
(1-2 acres/MGD)
- Improved aquatic plant
growth.
- More stable year-round
«perations.
Figure 2. Upgrading wastewater treatment lagoons by use of controlled
aquaculture processes.
environment
130
-------
isms throughout the winter. Solar heated
tank temperatures in the San Diego
climate averaged 75-85°F, whereas out-
side uncovered pond water temperatures
averaged 40°F during the same winter
months.
Designing the Controlled Environment
Aquaculture Process for Sewage
Treatment
Based on the success experienced
with the high loading rates utilized
in the controlled environment aqua-
culture system incorporating the inte-
grated biological and physical com-
ponents, the system was modified to
test its performance using domestic
sewage as the nutrient input source.
The major objective in modifying the
system for wastewater treatment was
to incorporate biological and physical
components in a manner which would
maximize process stability and reli-
ability on a year-round basis. This
objective was considered most important
because it is the main shortcoming of
both conventional lagoon processes and
conventional high technology processes to
date. A second major design objective
was to combine the best design and
SECTION VIEW - SOLAR AQUACELL SYSTEM
SOLAR ENERGY
DOUBLE POLYETHYLENE
AIR INFLATED ROOF
DUCKWEEDS
SURFACE AERATOR
WITH CAGE (OPTIONAL)
WATER HYACINTHS
"" "
CONCRETE POST
& FOOTING
BIO-WEB SUBSTRATES
FOR ATTACHED
MICROORGANISMS
AERATION
PROVIDES
GENTLE MIXING nirrcTc
Ulbtbli
ANAEROBICALLY
Figure 3. Section view of solar AquaCell lagoon system.
131
-------
operating features of the "soft" tech-
nology lagoon processes with their
low construction and operating cost,
with the reduced land requirement of the
more controlled, but expensive "hard"
technology systems. The hybrid process
could then encourage the use of natural
biological lagoon systems for communities
unable to afford, or without access to
the large land areas required for con-
ventional oxidation ponds, and thus
forced to install high technology sy-
stems. The function and design objective
of the various components of the system
are discussed in more detail as follows.
Bio-Film Substrates
It is common practice in aquaculture
systems as well as wastewater engineering
to utilize high surface area substrates
for the attachment of nitrifying bac-
teria, and waste-consuming microorganisms
and invertebrates. In trickling filter,
bio-disc, or activated sludge processes,
simple materials such as rocks, redwood
lathe boards, fiberglass plastic sheets,
or sewage sludge itself is proven tech-
nology for providing substrate for
attachment of bio-film microorganisms.
Surface area requirements for conven-
tional trickling filter or bio-disc
processes typically range from 0.3 to
1.0 sq. ft. of total available surface
area per gallon of wastewater treated per
day, while retention times are only 4-6
hours to achieve secondary treatment
(WPCF, 1977).
Based on our experience with
acquaculture food production system,
we have found that plastic mesh webbing
material anchored on the bottom and
allowed to extend upwards through
the water column provides a simple,
inexpensive, yet very effective and
durable substrate for bio-film and
invertebrate growth (Figure 4). The
function of the Bio-Web substrate is
similar to the other well-proven con-
ventional processes. However, because of
the relatively low cost of earthen ponds
and the freely suspended Bio-Web sub-
strates, it is economical to design
lagoon processes with much higher bio-
film surface area to loading rate ratios
and with longer retention times. From
our studies, we have found that design
factors of 2-4 sq. ft. of surface
area/gallon treated/day, and 2-4 days
retention time are adequate for achieving
secondary to advanced tertiary treatment
(see following sections). Thus, the
combination of lagoons with bio-film
substrates can result in a design that is
more conservative, reliable, and eco-
nomical than high technology systems for
producing either secondary or higher
quality water.
Adding Bio-Web substrates to con-
ventional lagoons, which have only
the pond bottom as surface area for
attached microorganisms, can increase
this attachment area from 20 to 60 times.
In terms of bio-film treatment processes
only, the retention time could be reduced
to one-twentieth to one-sixtieth of that
required by conventional lagoons (this
estimate has been fairly well supported
by our experimental results, as discussed
later).
From a design viewpoint, the ad-
vantages of using biological substrates
in lagoon systems can be summarized as
follows, and as shown in Figure 4.
1) Reduction of BOD and suspended
solids by physical means, with the
Bio-Web substrates acting as a barrier to
cause coagulation and sedimentation of
the suspended organics, which are then
digested anaerobically on the pond
bottom.
2) The vertically suspended,
buoyant Bio-Web substrates maintain the
bacterial film in suspension without the
need for electricity (e.g. for aeration),
as is required for the complete mix
activated sludge process. Similarly, the
trickling filter process requires high
pumping costs to lift and recycle sewage
through the trickling filter media.
3) Elimination of ammonia from the
effluent, which otherwise exerts a high
biological oxygen demand on receiving
waters; and which can combine with
chlorine and produce toxic chloramines.
4) Nitrification of toxic ammonia
to non-toxic nitrate to allow growth of
organisms in succeeding cells, or if
reuse of nutrients of aquaculture food
production is desired.
5) By varying retention time, the
Bio-Web substrates can aid in producing
either secondary or advanced tertiary
quality effluent from the same lagoon
system.
6) The Bio-Web substrates also
provide extensive habitat for grazing
invertebrate detritivore organisms which
consume, concentrate, and metabolize the
organic and inorganic detritus material
adhering on the Bio-Web substates.
7) No structures are required to
support the Bio-Web, since it is a
low-density, floating material and only
needs to be anchored at the bottom. It
can be easily added to a pond system
without the cost of additional com-
ponents.
132
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Because our initial studies had
indicated that the great majority of
nutrients and organic matter was re-
cycled through the bacteria/detritus/
detritivore food chain rather than the
aquatic plant food chain, it was clear
that the Bio-Web substrate were the most
important elements in the integrated
AquaCell system, and their optimization
would need to be carefully considered.
1
FLOATING
AQUATIC
PLANT
ZONE
Nighttime
Oxygen Demand
Met By Air
Rather Than Water
BIO-WEB
SUBSTRATE
ZONE
(AEROBIC,
PARTIAL MIX)
ANAEROBIC
ZONE
IRECT UPTAKE 1 NH
OR ENTRAPMENT/ SS
BY AQUATIC ( BOD
PLANTS J PO
/ tlellVtiHL
BIO-WEB SUBSTRATES
NITRIFICATION
ASSIMILATION
OF ORGANIC
NITROGEN &
CARBON
Detritus
(Bacteria &
Fecal Matter)
COAGULATION,
PRECIPITATION 6,
Detritus
To Anaerobic
Sediments
SEDIMENTATION
OF ORGANIC
AND INORGANIC
SUSPENDED SOLIDS
(NO 0 REQUIRED)
Removal by
Harvest
With Plants
"ANAEROBIC as7 -.':
SLUDGE DIGESTION
Figure 4. Conceptual section view of the AquaCell pond showing three treatment zones
and function of Bio-Web substrates. BOD and nitrification aeration re-
quirements are reduced by harvesting, sedimentation, and anaerobic di-
gestion processes.
133
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Solar Greenhouse Pond Cover
Because wastewater treatment pro-
cesses must operate under all weather
conditions every day of the year, one
must design an aquaculture system that is
not susceptible to upset by freezing
conditions, invasion by predators which
might consume the aquatic plants, or
windstorms destroying the surface plant
cover by blowing it onto the shore. Even
if occurring only once a year, these
events would upset treatment operations
until regrowth occurred. This could, take
several months during winter periods.
Independent of the above risk
considerations, the cost savings provided
by a solar pond cover, in terms of
reduced costs for land and pond con-
struction, can easily justify its use
(Table 3). By maintaining higher pond
temperatures during the winter periods,
metabolic rates of bacteria, micro-
organisms, detritivores, invertebrates
and aquatic plants will be signifcantly
increased, which in turn greatly reduces
the retention time and land area re-
quired. For example, it is well re-
cognized that metabolic rates of most
organisms usually increase by a factor of
2.0 for every IQoc rise in temperature
(Barnes, 1937). This varies of course,
depending on the species and its physio-
logical tolerance ranges, but on the
average can mean that a pond maintained
at 15°C (59°F) will metabolize twice
the sewage load as an uncovered pond
operating at 5°C (J40°F).
Since most domestic sewage enters
the treatment facility at relatively
warm temperatures during winter periods
due to the extensive use of hot water in
most homes, the greenhouse pond cover
need only act as an insulation barrier to
maintain relatively warm pond operating
temperatures. Combined with the solar
Table 3. Comparison of average construction costs for
other lagoon systems for secondary treatment.
the solar AquaCell versus
Costs Per 1.0 mgd Facility
($1,000)
Oxidation
Lagoon
Retention
Land Area
(water
Time
Requirements
surface)
60 -
50 -
120
90
days
acres
Aerated or Water
Hyacinth Lagoon
12
8
- 25
- 20
days
acres
Solar AquaCell
Lagoon
2.0 -
1 -
3.
1.
0
5
days
acres
Land Costs/Acre
Pond Construction $/Acre
(includes piping, sealing,
gravel rock, access, etc.)
Total Land & Pond
Construction Cost
Other Components
- Aeration System and/or
Harvesting Equipment
(screening or sand
filtration may be
necessary)
- Greenhouse, Bio-Web
Substrates, Anaerobic Pond
Covers & Gas Collection,
Solar Heat Exchange Systems,
etc .
TOTAL LAGOON SYSTEM COST3
$2-5
$3 - 5
$225 - 900
-0-
-0-
$225 - 900
$2 - 10
$8 - 15
$80 - 500
$40 - 150
$120 - 650
$5 - 10
$25
$30 - 40
@ $350,000 acre
average cost =
$350 - 525
$350 - 565
Costs are for the lagoon system only, and do not include other variable costs
such as engineering, administration, headworks, sand filtration or screening, dis-
infection, pump station, etc. Assumes a minimum 3-Cell system for each process.
Land costs are highly variable. It is assumed oxidation lagoons would be most
suitable at lower land costs, while the AquaCell system would be better in higher
land cost situations.
134
-------
heat transfer, which can be considerable
even on cloudy days, it is possible for a
greenhouse covered pond system in north-
ern climates to have average operating
temperatures of 12-1?°C (54-63°F)
during a 4 day retention period. In
contrast, uncovered ponds have operating
temperatures of only 2-4oc (36-40°F).
Based on the metabolic rates of the
organisms, it is thus theoretically
possible to reduce the retention time and
land area to one half to one fourth that
of the exposed pond, due to improved
operating temperatures alone.
This reduction in retention time can
be carried further. During winter
periods when conventional lagoons are at
near-freezing temperatures, biological
activity and algal growth are essentially
stopped, yet the effluent quality in
terms of BOD and suspended solids is
satisfactory, primarily due to the lack
of algae. However, the accumulated
nutrients stored during the winter period
must then be digested during the spring
period of rising temperatures, along with
the continuously incoming sewage. The
greatly increased loads during spring
usually cause tremendous algae blooms,
and subsequent massive algae die-offs,
which create high oxygen demand and
anaerobic odor problems. Because of
these cyclical winter and spring upset
problems, conventional lagoons must be
designed 2-3 times larger than otherwise
required. The greenhouse pond cover can
greatly alleviate this problem by main-
taining higher winter operating tempera-
tures to allow more consistent biological
treatment of the sewage, and thus avoid
the large accumulation of sludge and
biological oxygen demand.
The high evapotranspiration rates of
aquatic macrophytes can increase water
losses of uncovered ponds from 2-7 times
the normal rate, or about 0.5 to 2.0 acre
feet per month (Del Fosse, 1977). In
water-short areas this can be a con-
siderable financial loss, and in areas
with high dissolved salts in the waste-
water, the increased salt content after
evaporation can render the water useless
for irrigation. With the use of a well-
sealed greenhouse pond cover, the evap-
orative losses are reduced to insignifi-
cant amounts, and the total dissolved
salts can be maintained or even reduced,
due to the net uptake of minerals by the
aquatic plants and pond invertebrates.
Thus, the greenhouse pond cover can be
very cost effective under conditions
where water is a valuable commodity.
In cold-climate situations, snow-
loads are not a serious concern because
the warm temperatures within the green-
house (including between the two plastic
roof membranes), and the pond, which
acts as a giant heat reservoir, quickly
melt any snow accumulating on the roof
membrane. Greenhouses are commonly used
in the hydrophonic vegetable and decora-
tive plant industry in northern climates
without experiencing serious snowload
problems. Greenhouse systems utilizing
douple-layer, air-inflated polyethylene
roofs have particular advantages in
retaining pond heat. It has been demon-
strated that such roofs can reduce heat
losses to 50 percent of greenhouses
with single-layer roof glazings con-
sisting of glass, fiberglass, or poly-
ethylene (Keveren, 1973).
RESULTS OF THE SOLANA BEACH
PILOT LABORATORY
Description of the System
Design and Operation
A pilot AquaCell system was con-
structed, in Solana Beach, Calif., in
August 1976 to demonstrate process
performance using domestic sewage. The
system consisted of a series of four
tanks averaging 1500 gallons each, and 6'
x 8' x 4.3' deep in size. Each tank was
constructed using wood framing, a hypalon
rubber liner, and plumbed for independent
sampling of each stage. A polyethylene
cover over the tank retarded evaporative
and heat losses, and the entire treatment
facility was contained within a 25' x 50'
greenhouse.
The source of sewage was a small
sewer line transversing the property
where the facility was constructed.
Sewage was pumped into the facility using
a submersible pump and flows were ad-
justed to average 1500 gallons per day to
achieve approximately one day retention
time per cell, or four days total.
Because the sewer line serviced only
about 18 houses, it often ran dry during
the late evening and early morning hours,
causing considerable problems in pump and
sewage flow maintenance. Consequently,
flows were adjusted to provide 1.5-2.0
gallons per minute for a 12-16 hour
period from about 8 AM until 12 midnight,
when a timer shut off the pump until
sewage began flowing the next morning.
Due to the difficulty of maintaining
steady sewage flows without considerable
operator maintenance, the facility was
operated at irregular flow rates in
between sampling periods in order to
"feed" the biomass.
Sewage entering the facility was
settled in a modified Imhoff conicle
tank where it received approximately
1 hour retention time. The sludge
was returned to the manhole. One week
before sampling, and throughout each two
week sampling period, sewage flows were
135
-------
carefully maintained at desired rates on
a daily basis. Sampling operations were
conducted approximately every 6 weeks for
an 8 month period from September 1976 to
March 1977. Although the fluctuating
sewage influent conditions created an
operational inconvenience, it actually
presented a more difficult test for the
treatment process than under consistent
flows and nutrient loading conditions.
Operational Results
Facility start-up consisted of
inoculation of the Bio-Web substrates
with bacterial, protozoan, and invert-
ebrate detritivore organisms cultured in
our aquacultural food production systems,
and stocking the tanks with water hya-
cinth and duckweed plants. Within 4
weeks time, a treatment effectiveness was
readily observed, and the aquatic plants
and snails were reproducing and growing
most vigorously in the first cell with
the high nutrient loading. As expected,
the amphipod and ostracod invertebrates
and small Gambusia (mosquito fish) were
thriving better in the second, third and
fourth cells, presumably due to the toxic
levels of ammonia in the first cell.
Detergent foams inhibited the growth of
duckweeds in the first cell, but had
little effect on the water hyacinths.
Full flow conditions (1500 gallons a
day) could be handled effectively within
3 months from start-up. The results of
water chemistry analysis for the main
wastewater parameters tested during the 6
month monitoring period from October
1976-March 1977 are presented in Figures
5a-7a. Analysis of BOD, suspended solids
and coliforms was made by Environmental
Engineering Laboratories, a certified
testing laboratory. Nitrogen, phosphate,
oxygen, pH, and temperature were analyzed
by Solar AquaSystems personnel, with
split samples verified by E. E. L.
The Bio-Web substrates were in-
stalled at densities of approximately 4.0
sq. ft. per gallon treated per day (6,000
sq. ft. of total surface area) in the
first three tanks only. The fourth
tank contained bio-film surface area
in the form of plastic mesh cages for
holding freshwater shrimp in individual
cells at high density. The third tank
contained five carp averaging 3 Ibs each
held within a net-pen. The purpose
of the fish and shrimp was to observe
their survival and growth within the
system and to observe their ability to
function as top trophic level consumers
by cropping the invertebrate detriti-
vores, which migrated steadily into their
cages and pens.
A diverse biological film of diatom,
some algae, and numerous bacterial and
fungal slimes grew on the Bio-Web sub-
strates in the first tank. In tht
following tanks, a much thinner film
developed, consisting primarily of
bacteria and diatoms which were well
grazed by ostracods, protozoa, amphipods,
and snail detritivores. During the
eight month period the substrates were
never observed to accumulate a film
thicker than approximately 0.8 milli-
meters on either surface. A detritus or
sludge layer that might be expected to
accumulate on surfaces in conventional
sewage systems did not build up. This is
apparently due to the continual sloughing
off of the vertically oriented and
continuously flexing bio-film, as well as
to grazing by the detritivore inverte-
brates. The sloughing off process appears
to function independently of, and without
need for, the grazing process, because
during periods when the first cell
contained few invertebrates, the bio-film
layer did not increase.
Sludge build-up was monitored in the
bottom of all four tanks. Results
indicate that the anaerobic layer on the
bottom of the first two cells was ef-
fective in reducing sludge build-up.
After eight months operation, there
remained only about 10 mm of sludge
in Cell #1, 5 mm in Cell #2, and less
than *t mm of sediment in the remaining
two cells.
The polyethylene greenhouse cover
and the solar spraying heat transfer
system operated effectively to heat the
water during the winter, and cool the air
during summer periods. Water tempera-
tures could be increased on the average
of 1.0°C per cell per day during the
summer periods, and maintained equal to
influent temperatures (approximately
21°C) during the fall months. During
winter, water temperatures dropped an
average of only 0.5°C per day, aver-
aging 18°C influent, and 16°C during
the coldest winter periods when external
air temperatures averaged 10°C daily.
Water treatment effectiveness did not
reduce substantially during the winter
periods as expected. Suspended solids
and BOD treatment continued at efficien-
cies close to fall periods, but nitrogen
removal rates decreased as anticipated
due to decreased growth of aquatic plants
and food chain organisms. Detailed
analysis of winter period performance
will be -carried out with the new Cardiff
facility.
CARDIFF AQUACELL DEMONSTRATION
FACILITY
Due to the limited sewage flow
available at the Solana Beach site, a new
136
-------
AquaCell was constructed at the San Elijo
Treatment Facility in Cardiff, Califor-
nia. The facility, operated by the
County of San Diego, provides primary
treatment and ocean discharge of two
million gallons per day of domestic
sewage. At this new location either raw
or primary treated effluent can be
obtained dependably on a continuous
basis, and the flow represents a more
typical cross-sect ion of municipal
wastewater.
The Cardiff AquaCell facility is
designed to approximate full-scale design
parameters in terms of surface area to
volume ratio, aeration rates, sewage
loading rates, aquatic plant cover, etc.
The AquaCell tanks were constructed as
three cells in series, each 8' x 13' x 5
1/2' deep, and approximately 4,000
gallons capacity per cell. Design flow
rates are from 2.0 to 4.0 gal/minute or
3,000 to 6,000 gal/day to allow 2-4 day
retention time. Pretreatment will
consist of a two-stage anaerobic tank
(1,200 gallons capacity, Stage 1; 2,400
gallons capacity, Stage 2). The first
stage is designed to function as the
sedimentation and acid fermentation
stage, and the second primarily as the
methane fermentation stage, thereby
improving treatment reliability, gas
production, and sludge digestion. The
anaerobic primary system has just re-
cently been completed and operational
data are not yet available.
The three AquaCell tanks are plumbed
with header pipes at each end to distri-
bute flows and minimize short-circuiting.
The effluent and influent piping to each
tank is plumbed to also allow either
parallel or series flow operations, but
to date has only been operated as series
flow.
Cell #1 contains both diffused and
surface aerators, while Cells #2 and 3
are aerated with only diffused aeration.
The air diffusers are mounted approxi-
mately 1 foot off the bottom in order
to minimize stirring of benthic sediments
and to encourage the development of an
anaerobic sediment digestion layer.
200
175 '
150 '
125
100
LT>
ca
75
50
25
*(262)
0 D c 8 D 0
a) SOLANA AQUACELL
(Oct.'76 - Mar. 77 )
X-
Ave. of 20
points
BOD 5 8 D 0
b) CARDIFF AQUACELL
(June- Sept., 1978)
D.O.
— — —O—
10 g:
o
<=>
5 601 2
DETENTION TIME (DAYS)
AquaCell demonstration facilities,
137
-------
A slow-sand filter (0.1-0.2 gpm/sq.
ft.) at the end of Cell #3 functions
primarily as a screening device to remove
invertebrate organisms, aquatic plant
root fibers, and any re-suspended detri-
tus. Sand particle size in the sand
filter averages 1.0 mm, ranging from
0.5-2.0 mm in diameter. The sand filter
has only required one back flushing
during the first four months of continu-
ous operation. Data presented in the
following figures do not include sand
filtration.
Biological Components
Biological components of the
Cardiff AquaCell are similar to those
of the Solana Beach facility. Aquatic
plants consist of both water hyacinths
and duckweeds (Lemna minor, Spirodella
.§££•> Wo_lfi^a j3££. ) . The only fish
stocked in the facility were Gambusia
to control any mosquitos which might
find their way into the tanks through
open vents or doors. In order to demon-
strate that the higher food chain organ-
isms are not necessary for the treatment
process, no other fish or shrimp were
stocked during the first four months
of operation. The Bio-Web substrates
were installed at densities of 3 sq.
ft. of total available surface area per
gallon treated per day at the 3,000
gallon/day loading rate. The bio-film
thickness was measured after three months
operation and found to average 0.7 mm in
Cell #1, 0.08 mm in Cell //2, 0.02 mm
in Cell #3. The number of organisms
per square millimeter was substantially
greater in the first cell, but the
diversity of microorganisms was greater
in the second and third cells, as common-
ly observed in progressively cleaner
zones of polluted streams (Hart and
Fuller, 1971). Start-up operations were
conducted for a one month period and
consisted of inoculating the three cells
with bacteria, sludge, detritus, micro-
organisms, amphipods, snails, and other
detritivore invertebrates maintained in
continuous culture in our aquaculture
food production systems at a separate
aquaculture facility.
Treatment Performance
and Discussion
Results of chemistry analysis for
the first four months operation indicate
a)
SUSPENDED SOLIDS
SOLANA AQUACELL
(Oct. 1976 - Mar. 1977)
SUSPENDED SOLIDS
CARDIFF AOUACELL
(June - Sept. 1978)
Ave. of
15 points
5 60 1 2
DETENTION TIME (DAYS)
Figure 6a & b. Suspended solids treatment performance for Solana Beach and Cardiff
solar AquaCell demonstration facilities.
138
-------
treatment performance is similar to the
Solana Beach facility. The chief dif-
ferences are due to the influent sewage,
which is substantially higher in BOD and
ammonia at the Cardiff site. Even though
treated by one hour sedimentation, the
primary effluent is more typical of raw
sewage and requires greater retention
time than the relatively weaker sewage at
the Solana Beach facility. This can be
seen by comparing Figures 5a and 7a with
5b and 7b, showing the relative BOD and
ammonia, nitrite, and nitrate levels
over 4-6 days retention time. The BOD
loading rate of 3,000 gpd at the Cardiff
AquaCell has been equivalent to 1,800
Ibs/acre/day in Cell #1 only, or an
average of about 600 Ibs/acre/day in all
three cells. The higher BOD and ammonia
loading rates also required considerably
more aeration, which resulted in a water
mixing rate too high to properly maintain
the first cell as a facultative pond.
Oxygen levels averaged 0.5 to 2.0 ppm in
the upper half of the first cell, but
dropped to only 0.5-1.0 ppm near the
bottom. Preliminary observations of the
system with the anaerobic stages in
operation indicate the reduced BOD load
permits reduced aeration, mixing, and
allows more effective facultative opera-
tion in the first cell.
The high ammonia and BOD levels also
reduce dissolved oxygen in Cell #2 and 3,
thereby inhibiting nitrification, and
causing higher BOD measurements at days
3 and 4 due to the remaining ammonia.
(Nitrification of ammonia to nitrate re-
quires 4.2 mg/02/mg/NH3 , or nearly
four times the amount per mg of carbona-
ceous BOD.) Preliminary results with
the anaerobic primary unit in operation
indicates higher dissolved oxygen (3-4
ppm), lower ammonia, and lower BOD in
Cells #2 and 3- Suspended solids have
been steadily maintained at 2 to 8 ppm
in final effluent after the start-up
phase.
It is interesting to note that a
secondary quality effluent could be
achieved within two days retention time
(1-1/2 cells), during which only the
time in Cell #2 provided exposure to
aquatic plants. It is clear from
operational results, as well as existing
bio-film type treatment processes, that
40
35 .
30
25
20
15 .
10 .
NITROGEN
a) SOLANA AQUACELL
(Oct. '76 - Mar. '77)
NITROGEN
/ \\\ Ave.
/ \\ 40 ppm
Ave. V * influent
• lr?Pm * \* b) CARDIFF AQUACELL
influent \ . a
\\ (June - Sept. '78)
• \
X /No2 :x.
-^•--^r-< • >^.-
5 601 2
DETENTION TIME (DAYS)
M-
3
Figure
-
Cardiff AquaCell facilities.
139
-------
secondary treatment can be achieved with-
in short retention times using only the
Bio-Web substrates. In contrast, use of
only water hyacinths requires a minimum
of 15-20 days (average year-round) to
achieve secondary treatment (Wolverton,
1978; Del Fosse, 1977). The advantages
of incorporating aquatic plants can be
numerous, as previously discussed, but
the plant species and method of use must
be based on a thorough analysis of over-
all treatment and design objectives.
Effluent phosphate levels have been
highly variable, due primarily to the
widely fluctuating input levels (10-30
ppm) and short retention time masking
the relatively low removal rates. Esti-
mates based on limited data suggest
averages of 0.5-1.0 ppm total phosphate
removal per day retention time can be
expected.
Total coliform reduction occurred
rapidly (Figure 8) suggesting the need
for only low doses of chlorine or ozone
to meet most discharge criteria.
Total dissolved salt studies have not
yet been carried out, awaiting completion
of a relatively air-tight cover to ap-
proximate full-scale greenhouse operating
conditions. Limited data from the Solana
Beach AquaCell unit indicated reduction
ranging from about 0-300 ppm (0-30 per-
cent), but were highly variable. Dinges
(1978) reported average TDS reductions up
to 50 percent in a water hyacinth channel
receiving secondary treated sewage. The
biomass mineral uptake cannot account for
more than 5-10 percent of the reduction
Dinges or we observed. Humic acids are
produced during the breakdown of aquatic
macrophytes in the benthic layer.
Chelation/humic colloid precipitation
processes by humic acids are well known
(Ruttner, 1963), and undoubtably account
for this variable but potentially very
useful process for TDS reduction.
During startup operations and first
two months of steady flow, the sewage was
entirely shut off for periods from 3-8
days on three different occasions. When
sewage was returned to full flow, treat-
ment effectiveness was reachieved within
two days, attesting to the stability and
elasticity of the bio-film and floating
macrophyte plant process.
The data presented in Figures 5-7
suggest the functioning of the system
is a fairly linear process, typical of a
zero order reaction. The water quality
improves in direct relation to retention
time. This is in contrast to most lagoon
processes which are subject to the fluc-
tuating and often opposing processes of
sedimentation, clarification, algae
growth, die-off, nutrient release and
regrowth, and so on, until eventual net
stabilization of organic matter is
gradually achieved after 50-150 days
retention time. The rate of nitrifi-
cation ranged from 0.1-0.3 lbs/day/1,000
sq. ft. of Bio-Web surface area, depend-
ing on dissolved oxygen levels (including
the nitrification and/or ammonia removal
by the hyacinths and duckweeds) . This
compares favorably with the 0.32-0.55
lbs/day/1,000 sq. ft. rate observed by
Abd-El-Bary and Eways (1978) using
fixed-films for nitrification.
Energy Considerations
Energy requirements of the AquaCell
system are being monitored by use of air
flow metering devices and by calculating
electrical demand of the surface aerator
and diffused air compressor. Modifi-
cations were made in the analysis to
account for lack of efficiency with the
small aeration devices used. Based on
expected air volumes, transfer ef-
ficiencies, horsepower requirements
for a full-scale system, the energy
requirements for the present loading
rates are equivalent to approximately 25
Hp per mgd. We estimate this power
requirement can be reduced to 15-20 Hp
per MGD with the anaerobic pretreat-
ment process, depending on effluent
quality desired.
In terms of energy requirements, the
AquaCell process is similar to an aerated
lagoon. Under conditions of high BOD,
ammonia, and water temperature, it can
require more aeration, primarily due to
more complete nitrification and BOD
reduction, and the production of advanced
tertiary rather than secondary quality
water. The preliminary results to date
suggest the process requires considerably
less energy than theoretical estimates,
based on carbonaceous and nitrogenous
BOD, would indicate.
As shown in Figure 4, aeration and
oxygen demand are reduced by a number of
natural processes, including: 1) direct
uptake of ammonia and nutrients by the
aquatic plants, which exchange oxygen
and carbon dioxide through the air,
thereby decreasing and stabilizing oxygen
demand, particularly during nocturnal or
low-sunlight hours; 2) direct entrapment
and removal of particulate BOD by plant
harvesting; 3) coagulation and sedi-
mentation of organic suspended solids by
the Bio-Web substrates, followed by
anaerobic digestion on the pond bottom;
4) passive oxygen exchange through the
water surface, assisted by gentle mixing
from submerged diffused aerators; 5) no
aeration requirements to suspend the
microorganisms, since the Bio-Web sub-
140
-------
\X 110
50
o
X
o
CD
=3
O
TOTAL CPU FORM
• • Cardiff AquaCell
Solana AquaCell
After
Sand Filter
2 3
DETENTION TIME (DAYS)
Figure 8. Average total coliform reduction in relation to detention time.
strates are buoyant and the ponds are
operated only as a low-mix process; 6)
the aquatic macrophytes and detritivore
invertebrates convert nutrients into a
form which remains stable until harvest.
On-line or backup excess aeration is not
required to provide for "upset" periods
characteristic of algae or bacterial
systems.
THE CITY OF HERCULES SOLAR
AQUACELL ADVANCED TREATMENT
FACILITY
The City of Hercules, 30 miles north-
east of San Francisco, California, is
presently constructing a 0.35 mgd, 1.5
acre lagoon treatment system using the
Solar AquaCell Process. Upon successful
operation of this first phase, the facil-
ity will be expanded to 6 acres of
AquaCells for treating 2.0 mgd of raw,
domestic sewage to advanced tertiary
quality as the community grows over the
next five to teh years. The facility is
expected to begin start-up operations by
March, 1979, approximately 5 months from
start of construction,''
facility is 100 percent fi-
nanced by the city and is designed joint-
ly by Solar AquaSystems and KCA Engi-
neers.
Facility Design
The Hercules facility is designed as
a three phase system consisting of a two
stage anaerobic pond, followed by a
facultative lagoon, and a final third
phase aerobic lagoon, as shown in Figure
9. In the ultimate facility, three
independent facultative/aerobic pond
units will be operated in parallel to
allow the city flexibility to select and
more efficiently meet changing water dis-
charge or reuse needs. By varying the
wastewater flow to either of the three
ponds, detention time can be either in-
creased to produce a higher quality ef-
fluent for industrial reuse, or decreased
to produce a secondary quality effluent
for land application or discharge. The
flexibility provided by the AquaCell
lagoon process was .a major advantage
desired by the city to allow process
optimization under changing regulatory
or environmental conditions, water
availability, and reuse market demands
over the next 30 years.
Pretreatment will consist only_ of
grinding (comminutor) in order to mini-
mize clogging problems during periodic
removal of sludge from the anaerobic
pond. The two stage anaerobic ponds are
designed to provide approximately 20 hour
total detention time, with the first
stage designed to operate primarily as
the sedimentation and acid fermentation
141
-------
stage, and the second stage as the
methane fermentation stage. This will
allow more control, stability and treat-
ment efficiency of the anaerobic process.
Both anaerobic ponds will be covered with
floating hypalon type rubber covers with
gas collection channels. The black
covers will function as solar heat
absorbers, and insulate against heat
losses, in order to maintain higher
operating temperatures and improve winter
period treatment. The combination of
aerobic with anaerobic ponds has the
further advantage of balancing out sea-
sonal differences in treatment efficiency
between the ponds. The anaerobic phase
will function better during the winter,
due to improved sedimentation and reduced
sludge digestion and thereby counteract
the slightly decreased operating ef-
ficiency of the aerobic AquaCells during
winter. During the summer periods, the
reverse trend will occur. The increased
sludge digestion in the anaerobic pond
will decrease its effluent quality, while
the facultative and aerobic AquaCells
will produce higher quality effluent due
to higher operating temperatures and in-
creased aquatic plant and bacterial
metabolism and growth.
The facultative and aerobic treatment
phases are combined in the same earthen
pond, with a hypalon curtain wall hydrau-
lically separating and providing a chan-
nel for the facultative treatment area.
The hypalon curtain wall is integrated
with the greenhouse columns, and there-
fore is relatively inexpensive to con-
struct. The facultative stage is design-
ed for approximately 24 hour retention
time. Its function is threefold: 1) to
PROPOSED 2,0 MGD SOLAR AQUACELL FACILITY - CITY OF HERCULES
FACULTATIVE CELL
SOLAR AQUACELL 3
(AERORIC)
ANAEROBIC POND
(floating cover
ANAEROBIC POND
(floating cover
FACULTATIVE CELL
SOLAR AQUACELL 1
(AEROBIC)
2 acres
SOLAR AQUACELL 1
(AEROBIC)
2 acres
aquatic plant
I recycling area
|(compost & Bio-gas)
I ' I ^
sand filter,
ozone, pump
station, & oper-
ations bldg.
FACULTATIVE CELL
.influent
effluent
Figure 9. Plan view of the proposed 2.0 mgd Solar AquaCell Lagoon Treatment Facili-
ty for the City of Hercules, California. Each AquaCell will be 2.0 acres
(6 acres total). The 0.35 mgd treatment phase currently under construc-
tion consists of a 1.5 acre AquaCell system with anaerobic, facultative
and aerobic stages.
142
-------
reduce BOD by use of higher aeration than
will be maintained in the aerobic Aqua-
Cell stage; 2) to reduce BOD by means
of coagulation and sedimentation of sus-
pended solids via the Bio-Web substrate
mechanism, and; 3) to nitrify ammonia in
order to reduce toxicity in the following
aerobic stage. The facultative pond will
not contain water hyacinths or duckweeds,
in order to maximize oxygen exchange
through the surface. Diffuser pipes at
the influent and effluent ends of the
facultative and : aerobic ponds minimize
short circuiting problems.
In the aerobic Solar AquaCell pond,
oxygen levels will be maintained from 2
ppm at the influent to 6 ppm or greater
at the effluent end. Water hyacinths and
duckweeds will be cultured over the
entire water surface of this stage in
order to prevent growth of algae, to
assist the Bio-Web reduction of BOD, SS,
total nitrogen and phosphates, and to
produce a valuable by-product. Multiple
overflow screens will prevent escape of
detritivore invertebrates.
Projected Effluent Quality
Final effluent will pass through a
sand filter and ozone contact chamber to
assure advanced tertiary effluent for
industrial reuse purposes. Ozone treat-
ment was selected over chlorine, since
only relatively low doses of ozone will
be required with the low BOD, SS, and
ammonia effluent levels. Ozone treat-
ment can also have additional benefits
by oxidizing organic chemicals and pre-
venting the formation of toxic chlori-
nated hydrocarbons which would be caused
by use of chlorine.
If additional phosphate removal is
required for certain reuse purposes,
chemical addition could be minimal
because of the reduced interference from
BOD, SS, and"ammonia in the effluent.
With the quality of the water projected,
phosphate removal costs should be about
one-third of normal requirements.
For the northern California climate,
we estimate that approximately 1.5 acres
of Solar AquaCells (3 day retention time)
are required for 1.0 mgd flow (about
12,000 people) to achieve secondary ef-
fluent quality. Advanced tertiary (less
than 5 ppm BOD, SS, less than 10 ppm
total nitrogen, and insignificant levels
of ammonia, heavy metals and chlorinated
hydrocarbons) will require approximately
6 days retention time or 6 acres for 2.0
mgd.
Water and Aquatic Plant
By-Product Reuse
The high quality effluent will allow
multiple reuse options for the city. Two
local industries have expressed interest
in purchasing the water for process
operations. Greenbelt and forage crop
irrigation needs exist within the com-
munity, and two creeks, often dry through
most of the year, are suitable for en-
hancement or incorporation into a marsh-
wildfowl sanctuary.
The aquatic plants will be harvested
on a weekly or monthly basis, depending
on seasonal productivity, and converted
into organic compost in the first years
of operation. Digested sludge from
the primary treatment pond will be
removed approximately once every four to
six months, or as required, to be com-
posted together with the harvested plants
in order to improve the sludge texture
and dilute any possible concentrations
Of heavy metals to levels safe for
garden,use. In the final facility, the
possibility of converting all the aquatic
plants and sludge to methane gas will
be feasible, with the methane used
to operate the air compressors and
reduce total energy and operating costs.
Because of the success experienced to
date by Dr. George Allen (Allen et al.,
1977) with culturing salmon fingerlings
on natural food organisms grown in waste-
water lagoons, this possibility is being
considered for the Hercules project.
Salmon fingerlings would be cultured in
the net pens within the AquaCell ponds
for release down the creek enhanced by
the reclaimed water, out to the Pacific
Ocean, and to return 2-3 years later as
g private salmon run.
ACKNOWLEDGMENTS
The monitoring, sampling and chem-
istry analysis of the Cardiff AquaCell
facility was carried out by Jeannie
O'Toole of the Environmental Studies
Laboratory, University of San Diego.
Operation of the Cardiff AquaCell is
being managed by Andrew Holguin, Research
Associate of the Applied Aquatic Re-
sources Institute. Dr. Alice Jokela
provided valuable assistance with plan-
ning and analysis of the Solana Beach
pilot AquaCell project. This work has
been supported in part by Contract
#14-311-0017817 from the Office of Water
Research and Technology, U.S. Department
of Interior. Appreciation is extended to
the County of San Diego, Department of
Sanitation and Flood Control, for use of
the Cardiff Treatment Facility site.
143
-------
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Allen, Geo. H., and R. LeRoy Carpenter.
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Wastewater Renovation and Reuse,
Frank M. D'ltri (ed.), Marcel Dekker,
Inc. , New York.
Applied Aquatic Resources Institute.
1978. Progress Report to the Office
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Bagnall, L. 0. 1973. Use of Harvested
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Bardach, John E., John H. Ryther, and Win.
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Benetnann, John R., Ben Koopman, Daniel
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Cornell, David A., John Zolteck, Jr.,
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Del Fosse, Ernest S. 1977. Water
Hyacinth Biomass Yield Potentials.
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Hart, C. W., Jr., and Samuel L. H. Fuller
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Keveren, R. I. 1973- Plastics in
Horticultural Structures. Rubber
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Lecuyer, R. P., and Jerome H. Marten.
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267-86.
McKinney, R. E. 1974. State of the Art
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Middlebrooks, E. J., D. H. Falkenborg,
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PRWG159-1, 244 p.
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Growth of Selected Duckweeds,Lem-
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74 p.
Oswald, W. J. 1973. Complete Waste
Treatment in Ponds. Progress In
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Nitrogenous Wastes and Role of
Detritus in a Closed-cycle Poly-
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Department of Water Science & En-
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Davis.
Water Pollution Control Federation. 1977.
Wastewater Treatment Plant Design.
Lancaster Press, Lancaster, PA.
Wolverton, B.C., and Rebecca C. McDonald.
1978. Water Hyacinth (Eichhornia
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ing Studies. ERL Report No. 171,
March, NASA-N.S.T.L., Bay St. Louis,
Miss. 39529.
Wolverton, B. C. (ed.). 1978. Compiled
Data on the Vascular Aquatic Plant
Program: 1975-1977. NASA National
Space Technology Laboratories, Miss.
150 p.
Wolverton, B. C., R. C. McDonald, and J.
Gorden. 1978. Bioconversion of
Water Hyacinths into Methane Gas.
TX72725, July 1975.
Wolverton, B.C., and Rebecca C. McDonald.
1978. Nutritional Composition of
Water HyacLnths Grown on Domestic
Sewage. ERL Report No. 173, NASA,
National Space Tech. Lab., Bay St.
Louis, Miss.
145
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INTERMI TTENT SAND FILTRATION TO
UPGRADE LAGOON EFFLUENTS
James H. Reynolds, Jerry Russell, and E. J. Middlebrooks*
INTRODUCTION
Nature of the Problem
Wastewater stabilization lagoons
provide simple, efficient, and economi-
cal wastewater treatment for over 4,000
communities throughout the United
States. Approximately 90 percent of
these wastewater stabilization lagoon
systems serve communities having a
population of less than 5,000 persons.
These small communities are often lacking
in resources and competent person-
nel to operate and maintain sophisticated
wastwater treatment facilities.
Historically, wastewater stabiliza-
tion lagoons have provided adequate
wastewater treatment for these small
communities, however, wastewater lagoon
effluent may not meet present and future
stringent wastewater discharge standards.
In order to meet these stringent stan-
dards, an inexpensive treatment method
which does not require sophisticated
operation and maintenance and one which
is economical is needed for upgrading or
polishing lagoon effluents.
Intermittent sand filtration is
capable of polishing lagoon effluents
at relatively low cost. Intermittent
sand filtration is not a new technique.
Rather, it is the application of an old
technique to the problem of upgrading
lagoon effluents. Intermittent sand
filtration is similar to the practice
of slow sand filtration in potable water
treatment or the slow sand filtra-
tion of raw sewage which was practiced
during the early 1900s. Intermittent
sand filtration of lagoon effluents is
the application of lagoon effluent
on a periodic or intermittent basis to a
*James H. Reynolds is Assistant
Professor of Civil and Environmental
Engineering, Jerry Russell is a Graduate
Student, and E. J. Middlebrooks is
Dean, College of Engineering, Utah State
University, Logan, Utah.
sand filter bed. As the wastewater
passes through the sand filter bed,
suspended solids and organic matter
are removed through a combination of
physical straining and biological
degradation processes. The particulate
matter collects in the top 5 to 7.5
cm (2 to 3 inches) of the sand filter
bed. This buildup of organic matter
eventually clogs the top 5 to 7.5 cm (2
to 3 inches) of the sand filter bed
and prevents the passage of the effluent
through the sand filter. The sand
filter is then taken out of service and
the top layer of clogged sand is removed.
The sand filter is then put back into
service and the spent sand is either
discarded or washed and used as replace-
ment sand for the sand filter.
Objectives
The objective of this paper is to
discuss the use of intermittent sand
filtration to polish or upgrade waste-
water stabilization lagoon effluent.
Emphasis will be placed on intermittent
sand filtration research conducted by
Utah State University.
A historical perspective and review
of intermittent sand filtration has been
compiled by Hill et al. (1976) and Harris
et al. (1977) .
SINGLE STAGE FILTRATION
The development of intermittent sand
filtration to upgrade lagoon effluents
has been conducted primarily at Utah
State University (Marshall and Middle-
brooks, 1974; Reynolds et al., 1974a;
Harris et al., 1975; Reynolds et al.,
1974b; Hill et al., 1977; Messinger et
al., 1977; Bishop et al., 1976; Tupyi et
al., 1977). The work at Utah State
University has been conducted on labora-
tory scale, pilot scale, and field scale
filters. However, the principal work was
conducted on six prototype scale filters
shown in Figure 1. Each of these filters
was operated at a different hydraulic
loading rate for 12 months. The filter
146
-------
sand employed in the study was upgraded Table 1
pit run sand with an effective size of
0.17 mm (0.00? inch) and a uniformity
coefficient of 9.74 (see Table 1).
The biochemical oxygen demand
(BODg) removal performance for each
of the six filters is shown in Figure 2.
The overall average influent BOD5 con-
centration was 19 mg/1. The influent
BOD5 concentration ranged from 3.5 mg/1
to over 288 mg/1, exceeding 5 mg/1, 94
percent of the time. Figure 2 shows the
consistently high quality of filter
effluent, which was unaffected by in-
fluent BOD5 fluctuations. Effluent
quality was below 5 mg/1 93 percent of
the time (except filter number 2 during
the winter). The effluent BOD5 con- e = 0.170 mm;
Sieve analysis of filter sanda
(Reynolds et al., 1974).
U.S. Sieve
Designation
Number
3/8"
4
10
40
100
200
Size of
Opening
(mm)
9.5
4.76
_
0.42
0.149
0.074
Percent
Passing
(%)
100.0
92.1
61.7
27.0
6.2
1.7
9.74.
-LINER
SECTION 2-2 -
SAND AND GRAVEL PLACEMENT
SEAL
SCALE l"=6-0"
SEAL BETWEEN
LINER AND PIPE
1
t
\
\ ^
/
J_
/ \ ±
ER AND FILTER 3ED
PLAN VIEW
1 \ i
2 «-*
l /
y /
i
i
N
i
i
i
1
1
A A\ ^
•S
l\
\
--DRAIN PIPE
1
t
\ T \SEAL BETWEEN
1 LINER AND PIPE , ,
SCALE 1=10-0
LINER
SEAL BETWEEN DRAIN PIPE
AND LINER WITH SUITABLE
MATERIAL
SECTION I-
LINER SECTION
SCALE' |"= |0-0
Figure 1. Cross section of a typical intermittent sand filter (Harris et al., 1975).
L47
-------
O INFLUENT
A EFFLUENT
JUL AUG SEP QCT NOV
TIME IN MONTHS (1974-1975)
Figure 2. Single stage intermittent sand filtration
biochemical oxygen demand (8005) removal
performance.
JUL ' *UO ' MP ' OCT ' NOV ' DEC ' J«H ' FEB ' M»R ' APR ' M»r ' JUN
TIME IN MONTHS (1974-1975)
Figure 3. Single stage intermittent sand filtration
suspended solids removal performance
(Harris et al., 1975).
-------
centration never exceeded 11.8 mg/1 and
exceeded 7 mg/1 only four times during
the study.
The winter operation of filter
number 2 was different from the other
filters. Filter number 2 was operated in
a constant flooded mode during winter
operation. This constant flooded mode
was an attempt to improve winter opera-
tion. However, the anaerobic condition
that developed due to this constant
flooding greatly reduced the filter
efficiency. The effluent BOD5 con-
centration for filter number 2 exceeded 5
mg/1 92 percent of the time. At the end
of the winter operation, filter number 2
was returned to normal operation and as a
result the filter effluent returned to
normal when compared to the other filters
in the study.
Suspended solids removal performance
of the filters is shown in Figure 3.
The influent exceeded 5 mg/1 suspended
solids concentration, 100 percent of the
time and was greater than 30 mg/1 44
percent of the time. The average in-
fluent suspended solids concentration was
31 mg/1 with a low of 5.5 mg/1 and a high
of 130.2 mg/1. The three filters in
operation at the time of maximum influent.
suspended solids (130.2 mg/1) had ef-
fluent suspended solids concentrations of
less than 3 mg/1.
The initial loading period (Figure
3) shows a relatively high concentra-
tion of suspended solids in the filter
effluent. This is primarily due to
the "washing" of fine dirt (inorganic
fine) from sand during the start-up
period. After this initial start-up
period, the filter effluent exceeded
5 mg/1 suspended solids only 15 percent
of the time and had averages of less
than 6 mg/1. Seldom did the effluent
exceed 10 mg/1. The anaerobic con-
ditions of filter number 2 during winter
operations caused its effluent to
exceed 5 mg/1 83 percent of the time.
The suspended solids concentrations
from each filter were consistently
low.
The length of filter runs achieved
during this study was a function of the
hydraulic loading rate and the influent
suspended solids concentration. Filter
run lengths ranged from 8 days at a
hydraulic loading rate of 9,360 m3/ha.d
(1.0 mgad) during the summer months to
188 days at a hydraulic loading rate of
1,872 m3/ha.d (0.2 mgad) during winter
months.
Intermittent sand filters should be
similar in design to those illustrated in
Figure 1 with hydraulic loading rates of
2,744 to 5,616 m3 ha.d (0.4 to 0.6
mgad). Filter sands should have an
effective size of 0.15 to 0.25 mm (0.006
to 0.010 inch) with a uniformity coef-
ficient (Fair et al., 1968) from 1.5 to
10. The expected filter run length from
intermittent sand filters designed on the
above criteria will depend on the filter
influent quality, but should be a minimum
of 30 to 60 days.
These results (Harris et al., 1975;
Reynolds et al., 1974; Reynolds et al.,
1975) clearly indicate that intermittent
sand filtration of lagoon effluents can
produce a final effluent with a BOD5
concentration and a suspended solids
concentration of less than 15 mg/1
consistently throughout the entire year
even during periods of sub-zero tempera-
tures.
EFFECT OF SAND SIZE
ON SINGLE STAGE
PERFORMANCE
Tupyi et al. (1977) studied the
effect of various size filter sands
on intermittent sand filter performance.
The work employed the same filter
system as Harris et al. (1975) (see
Figure 1) except the effective size
of the filter sand employed for the
various filters was 0.68 mm, 0.40 mm,
0.31 m'm, and 0.17 mm. Hydraulic loading
rates ranging from 1871 m3/ha.d (0.2
mgad) to 28,061 m3/ha.d (3.0 mgad)
were studied. In addition, appli-
cation rates ranging from 0.008 m3/sec
(0.29 cfs) to 0.048 tn3/sec (1.74 cfs)
were investigated.
The biochemical oxygen demand
(6005) performance of all the inter-
mittent sand filters with respect to
various effective size sands, hydraulic
loading rates and application rates is
recorded in Table 2 and illustrated in
Figure 4. Yearly average BODg con-
centration in the effluent applied to the
filters was 11 mg/1 with the daily BODc
concentration ranging from 3 mg/1 to 22
mg/1 throughout the study.
The BODc; removal performance of
the 0.40 mm and 0.68 mm effective size
sand (Filters No. 2, 3, 4 , and 5)
with a high application rate of 0.048
m3/sec (1.68 cfs) was not adequate to
produce an effluent that was consistently
less than 10 mg/1. The 0.31 mm effective
size sand (Filter No. 3) produced a
significant BOD5 removal; however, the
influent characteristics during this
phase of study indicate that these
results were inconclusive. Lowering the
application rate on the 0.40 mm effective
size sand (Filter No. 5) and the 0.68 mm
effective size sand (Filter No. 4)
appeared to increase BOD5 removal; how-
149
-------
28,061.8 m*/n-d 130MGAQI Auguii 13,1975 la Auguil 17, 19'
18,707.9 mVh-d (2 0 MGAQ) Auqull 27, 1975 16 July 8. i9'76
9,353.9 ms/h-d tl.O MB AD I July iS, 1976 to AU?U*T 25, 19?
0 048
-------
Table 2. A summary of the 5-day biochemical oxygen demand performance
Effective
Size
Filter
Sand
(mm)
0.17
0.17
0.31
0.31
0.40
0.40
0.40
0.40
0.40
0.68
0.68
0.68
0.68
0.68
0.40
Influent
BOD5
Hydraulic
Loading
Rate
(n»3/h.d)
1,870.8
3,741.6
9,353.9
9,353.9
9,353.9
9,353.9
14,030.9
18,707.9
28,061.9
9,353.9
9,353.9
14,030.9
18,707.9
28,061.9
9,353.9
Appli-
cation
Rate
(m3/sec)
0.048
0.048
0.048
0.008
0.048
0.008
0.048
0.048
0.048
0.048
0.008
0.048
0.048
0.048
Loaded
0.008
Effluent
unnS
(mg/1)
Min.
2.6
2.6
4.5
9.7
2.6
4.5
9.8
2.6
9.8
2.6
3.7
4.4
2.6
6.3
With Primary
9-1
Max.
22.3
22.3
20.8
9.7
22.3
19.8
11.5
22.3
9.8
22.3
20.8
12.9
22.3
12.9
Lagoon
75.6
Ave.
10.9
11.5
13.8
9.7
10.5
12.2
10.7
11.3
9.8
11.6
13.2
7.8
11.5
9.4
Effluent
26.8
Min.
0.3
0.1
5.0
6.1
3.7
3.7
3.9
2.6
4.5
4.1
2.9
4.0
3.2
2.9
Twice Weekly
3.7
(mg/1)
Max.
3.7
7.4
11.2
6.1
17.8
11.0
6.0
23.3
4.5
17.3
15.4
6.8
15.6
11.9
28
Ave.
1.1
2.6
7.8
6.1
8.2
5.4
5.0
8.6
4.5
8.2
7.9
5.7
9.0
6.8
10.5
Average
Percent
Remova 1
90.1
77.2
43.5
33.7
21.9
56.0
53.3
23.9
54.6
28.8
39.8
27.5
21.0
27.1
60.8
ever, the zooplankton in the influent
during that experiment make s-uch a
conclusion questionable. The 0.17
mm effective size sand (Filters No. 1 and
6) was shown to be capable of high BOD^
removal at low hydraulic loading rates of
3742 m3/ha-d (0.4 mgad) and 1871 m3.ha-d
(0.2 mgad). No conclusion can be es-
tablished with relation to the Federal
Secondary Treatment Standards which
requires an effluent BOD5 of 30 mg/1
BOD5 con-
or less because the influent
centration did not exceed 2 3" mg/1
during the entire study period.
Suspended solids (SS) removal by
intermittent sand filters with various
effective size filter sands, hydraulic
loading rates, and application rates
are shown in Table 3 and Figure 5. The
mean yearly influent suspended solids
concentration (secondary lagoon effluent)
was 23 rag/I' and the daily SS concentra-
tion ranged 3 mgVl to 65 mg/1.
The 0.68 mm, 0.40 mm, and the 0.31
mm effective size sand (Filters 2, 3, 4,
and 5) with a high application rate of
0.048 m3/sec (1.68 cfs) were unable to
satisfy a 10 mg/1 standard more than 50
percent of the time. Lowering the ap-
plication rate to 0.008 m3/sec (0.29
cfs) on the 0.68 mm and 0.40 mm effective
size sand filters (Filters No. 4 and 5)
increased suspended solids removal
performance and meeting a 10 mg/1 stan-
dard a minimum of 67 percent of the time.
The indication that influent suspended
solids significantly influence effluent
suspended solids concentrations preclude
the use of these filter sands to satisfy
stringent discharge standards. It
appears that lower application rates
increase SS removal, but a definite
conclusion cannot be reached due to the
short period of study at the lower
application rates and the heavy growth of
Daphnia in the secondary lagoon effluent
during the low application rate study.
The 0.40 mm effective size sand
(Filter No. 2) with a hydraulic loading
rate of 9,354 m3/ha.d (1.0 mgad) and a
low application rate of 0.008 m3/sec
(0.29 cfs) loaded with primary lagoon
effluent twice weekly produced high
SS removals. Suspended solids removal
averaged 76 percent during the study
and further indicates that application
rate may have a definite effect on SS
removal. However, operation of this
filter does not represent normal single
stage intermittent sand filter operation
since lagoon effluent was applied
to the filter only twice weekly, rather
than daily.
151
-------
FILTER 6
—O— INFLUENT
—A— EFFLUENT
O.I7mw (O.OOSTtneO) Effvcti** Stit Sand
IBTO.Bin'/h-d {O.ZM3AD)
0.04«m'/»»e (l.fiBcfi)
TIME IN MONTHS (1975-1976)
Figure 4. The weekly 5-day biochemical oxygen demand performance.
152
-------
Table 3. A summary of the suspended solids performance.
Effective
Size
Filter
Sand
(mm)
0.17
0.17
0.31
0.31
0.40
0.40
0.40
0.40
0.40
0.68
0.68
0.68
0.68
0.68
Hydraulic
Loading
Rate
(m3/ha.d)
1,870.8
3,741.6
9,353.9
9,353.9
9,353.9
9,353.9
14,030.9
18,707.9
28,061.9
9,353.9
9,353.9
14,030.9
18,707.9
28,061.9
Appli-
cation
Rate
(m-Vsec)
0.048
0.048
0.048
0.008
0.048
0.008
0.048
0.048
0.048
0.048
0.008
0.048
0.048
0.048
Min.
3.2
3.2
8.2
20.0
3.2
12.2
34.3
3.2
44.9
3.2
8.9
17.7
3.2
33.2
Influent
SS
(mg/1)
Max.
74.3
74.3
64.8
20.1
51.5
35.9
44.9
64.8
44.9
51.5
74.3
51.6
51.5
51.6
Ave.
23.0
20.8
27.8
20.1
18.7
21.8
39.6
18.1
44.9
15.8
34.1
38.2
16.7
44.9
Min.
0.6
0.3
7.7
10.2
1.2
1.8
10.7
1.2
83.0
1.6
2.9
7.5
3.2
19.3
Effluent
SS
(mg/1)
Max.
23.8
17.6
29.2
21.0
30.8
16.0
12.5
39.8
83.0
25.2
39.7
30.0
24.4
57.8
Ave.
2.7
3.5
15.4
15.6
13.1
7.5
11.6
11.6
83.0
11.2
15.5
19.6
13.1
35.4
Average
Percent
Removal
88.2
83.0
44.6
22.4
30.1
65.5
70.7
35.9
0
29.3
54.7
48.6
21.6
21.1
0.40
9,353.9
Loaded With Primary Lagoon Effluent Twice Weekly
0.008 10.5 70.7 34.0 3.2
18.0
7.9
76.7
The 0.17 mm effective size sand
(Filters No. 1 and 6) with hydraulic
loading rates of 3742 mS/ha-d (0.4
mgad) and 1871 mS/ha-d (0.2 mgad) are
capable of meeting the 10 mg/1 standard
and the Federal Secondary Discharge
Standard of 30 mg/1.
A summary of filter run lengths with
the various size sands is shown in
Table 4. High hydraulic loading rates of
28,061.9 n)3/ha-d (3.0 mgad) produce
undesirable short filter run lengths for
0.40 mm (0.0158 inch) and 0.68 mm
(0.0268 inch) effective size sand filters
(Filters No. 2, 3, 4, and 5). Hydraulic
loading rates of 18,707.9 m3/ha-d (2.0
mgad) and less produce satisfactory
filter run lengths for the 0.40 mm
(0.0158 inch) and 0.68 mm (0.0268 inch)
effective size sand filters (Filters No.
2, 3, 4, and 5). The 0.17 mm 0.0067
inch) effective size sand filter (Filter
No. 6) with a hydraulic loading rate of
1870.8 m3/ha.d (0.2 mgad) did not plug
during the entire one year study. The
0.17 mm (0.0067 inch) effective size
sand filter (Filter No. 1) with a hy-
draulic loading rate of 3741.6 m3/ha-d
(0.4 mgad) produced satisfactory filter
run lengths. Due to insufficient data of
the 0.31 mm (0.0122 inch) effective size
sand filter (Filter No. 3) and the 0.68
mm (0.0268 inch) and 0.40 mm (0.0158
inch) effective size sand filters (Fil-
ters No. 4 and 5) with hydraulic loading
rates of 9353-9 m3 ha-d (1.0 mgad)
and a low application rate of 0.008
m3/sec (0.29 cfs), no conclusion can be
reached. However, data collected thus
far suggest that filter run length
may be increased by lowering the applica-
tion rate.
SERIES INTERMITTENT
SAND FILTRATION
In an attempt to increase the length
of filter run achievable with inter-
mittent sand filtration of lagoon ef-
fluent, Hill et al. (1977) conducted
laboratory and pilot scale studies on a
series arrangement of intermittent
sand filters. The experimental design
employed in these studies is shown
in Figure 6. Series intermittent sand
filtration involves the passage of
lagoon effluent through two or three
intermittent sand filters arranged in
series with progressively smaller effec-
tive size sands. Hill et al. (1977)
investigated three different hydraulic
loading rates on a pilot scale basis.
The weekly BODg removal perfor-
mance of the pilot scale series inter-
153
-------
Table 4. Filter run lengths achieved by
during the experimental period.
the various effective size sand filters
Volatile
Effective Hydraulic Appli- Suspended Suspended
Size Loading cation Solids
Sand Rate
(mm) (m^/ha
0.17 1,870
0.17 3,741
0.17 3,741
0.17 3,741
0.17 3,741
0.31 9,353
0.31 9,353
0.40 9,353
0.40 9,353
0.40 9,353
0.40 9,353
0.40 14,030
0.40 18,707
0.40 18,707
0.40 18,707
0.40 18,707
0.40 18,707
0.40 18,707
0.40 28,061
0.68 9,353
0.68 9,353
0.68 14,030
0.68 18,707
0.68 18,707
0.68 18,707
0.68 18,707
0.68 28,061
Solids
Rate Removal Removal
d) (m3/sec) (kg)
.8 0.048 121.03
6 0.048 14.19
6 0.048 29.69
6 0.048 55.95
6 0.048 75.56
.9 0.048 44.43
.9 0.008 5.45
.9 0.048 40.92
.9 0.048 59.10
.9 0.048 20.47
.9 0.008 42.06
.9 0.048 20.03
.9 0.048 15.25
.9 0.048 28.33
.9 0.048 0.00
.9 0.048 68.00
.9 0.048 87.01
.9 0.048 61.98
.9 0.048 0.00
.9 0.048 71.67
.9 0.008 124.20
.9 0.048 102.57
.9 0.048 51.31
.9 0.048 0.00
.9 0.048 101.26
.9 0.048 14.95
.9 0.048 46.36
(kg)
100.17
10.26
22.65
53.47
68.68
48.29
15.02
63.31
60.08
19.73
39.41
17.31
20.26
37.35
2.86
67.77
65.71
57.34
17.89
79.46
98.16
102.03
42.43
11.93
106.82
12.85
47.22
Method Consecutive
of Days of
Rejuvenation Operation
N.A. 280 and 94
Scraped 11
Scraped 36
Scraped and 166
Rested 14
days
N.A. 103
N.A. 45
N.A. 14
Scraped 44
Scraped 177
N.A. 17
N.A. 37
Scraped 6
Scraped 7
Rested 22 18
days
Scraped 6
Scraped 148
Scraped 42
Scraped 23
Scraped 3
N.A. 196
N.A. 84
Scraped 46
Rested 19 23
days
Scraped 19
Scraped 152
N.A. 11
Scraped 11
Loaded with Primary Lagoon Effluent Twice Weekly
0.40 9,353
0.5 mgad
4
0.72 mm
r
0.40 mm
1
0.17 mm
.9 0.008 62.25
72.74
I.Omgad
1
I
0.72 mm
i
0.40 mm
I
0.17 mm
N.A. 30
1.5 mgad
I
0.72 mm
i '
0.40mm
1
0.17 mm
T j
Figure 6. Series intermittent sand filtration of lagoon effluents (Hill et al., 1977),
154
-------
mittent sand filters is illustrated in
Figure 7. The influent BODc concentra-
tion varied from 4.1 mg/1 to 24.0 mg/1
and averaged 10.7 mg/1 during the
study. The final effluent BODc concen-
tration varied from 0.6 mg/1 at the
1H,031 m3/ha-d (1.5 mgad) hydraulic
loading rate to 4.2 mg/1 at the 9,353
mS/ha-d (1.0 mgad) hydraulic loading
rate. At no time did the final effluent
BODg concentration from the operation
exceed 5.0 mg/1. Statistical analysis
at the 1 percent level revealed that the
effluent BODc concentration was sta-
tistically identical at all three hy-
draulic loading rates for the 0.72
mm (0.0284 inch) and 0.40 mm (0.0158
inch) effective size sand filters.
The effluent BODjj concentration from
the 0.17 mm (0.0067 inch) effective
size sand filter at the 14,031 m3/ha-d
(1.5 mgad) hydraulic loading rate was
significantly higher (1 percent level)
than from the 9,353-9 m3/ha-d (1.0
mgad) and 4,677 m3/ha-d (0.5 mgad)
hydraulic loading rates. However the
actual numerical differences were small.
The weekly suspended solids removal
performance of the series pilot acale
field filters is shown in Figure 8. The
influent suspended solids concentration
ranged from 12.5 mg/1 to 69.4 mg/1 and
averaged 32.4 mg/1 for the study. The
final average effluent suspended solids
concentration ranged from 8.6 mg/1 for
the 4,677 m3/ha-d (0.5 mgad) hydraulic
loading rate to 6.4 mg/1 for the 14,031
m3/ha-d (1.5 mgad) hydraulic loading
rate. There was no significant dif-
ference (1 percent level) between the
final effluent suspended solids concen-
trations among the different hydraulic
loading rates.
Figure 8 indicates that at the
beginning of the study, the final ef-
fluent suspended solids concentration was
dependent upon the influent concentra-
tion. This was due to the "filter
.£ 10
Q
§ 5
. INFLUENT
0.72mm Effluent
. 0.40mm Effluent
0.17 mm Effluent
INFLUENT
0.72 mm Effluent
0.40 mm Effluent
0,17mm Effluent
JULY
AUG.
SEPT.
OCT.
NOV.
JULY AUG.
SEPT.
OCT.
NOV.
Figure 7. Weekly BOD5 removal perfor-
mance of pilot scale series
intermittent sand filtration
(Hill et al., 1977).
Figure 8. Weekly suspended solids
removal performance of pilot
scale series intermittent
sand filtration. (Hill et al.,
1977).
155
-------
washing" effect which takes place
during the initial start-up of intermit-
tent sand filters when inert fines
must be washed from the filter. When
this washing was completed, excellent
removals were obtained. At the end of
the experimental phase, when removals
were exceptional, the 0.17 mm (0.0067
inch) effective size sand filter ef-
fluent suspended solids concentration was
essentially independent of the in-
fluent concentration. The efficiency of
removal of intermittent sand filters
is increased as the "schmutzdecke"
(filtering skin) builds up on the surface
of the filters.
One of the main advantages obtained
with the use of a series intermittent
sand filtration operation is the in-
creased length of the filter runs. At
the time operations were suspended due to
freezing conditions (December 2, 1974),
all three filter systems had operated for
131 consecutive days without plugging.
Until the time operations ceased, the
applied influent loading passed complete-
ly through all three filters in the
series within 4 hours. It is difficult
to estimate the length of filter run
which could have resulted if freezing had
not occurred; however, based on the
data available, filter runs of at least
131 days may be obtained with a hydraulic
loading between 4,677 m3/ha-d (0.5
mgad) and 14,031 m3/ha-d (1.5 mgad).
Hill et al. (1977) conducted a
series of both laboratory and pilot
scale studies of series intermittent sand
filtration to determine the effect
of hydraulic loading rates on the length
of filter run achievable with three
stage series intermittent sand filtra-
tion. The results are summarized in
Figure 9. The results indicate that
hydraulic loading rates greater than
28,080 n)3/ha-d (3.0 mgad) signifi-
cantly reduce the length of filtration
run. However, Figure 9 neglects the
effect of influent suspended solids
concentration on filter run length.
Thus, variations to Figure 9 will occur
as the influent suspended solids concen-
tration varies.
•o
o
o>
UJ
or
z
o
o
_J
o
cr
o
x-
yj
cr
UJ
CO
a:
UJ
15.0
12.0
9.0
6.0
3.0
Loading
Kate
16-8-4 mgad
1 2-6-3 mgad
1 2 rm'.ad
8 mgad
8-4-2 mgad
6-3-1.5
4 mgad
4 mgad
3 mgad
1 .5 mgad
1 .0 mgad
0.5 mgad
Phase
III
III
II
II
III
III
11
IV
IV
1
1
1
Days lo
Plugging
1
1
3.5
5.5
7.5
9.5
16
21
27
> 131
~i 131
J= 131
Filler In
Series Plugged
0.72 mm
0.72 mm
0.17mm
0.17mm
0.72 mm
0.72mm
0. 1 7 mm
0.72 mm
0.72 mm
None
None
None
>I3I Days
at 1.5 mgod
10
20
30
40
50
60
70
80
LENGTH OF FILTER RUNS (Days)
Figure 9. Effect of hydraulic leaching rate on a three-stage series intermittent
sand filtration (Hill et al., 1977).
156
-------
The results of these studies indi-
cate that a three stage series inter-
mittent sand filtration system should be
designed with filter sands of effective
sizes between O.J2 mm (0.0284 inch) and
0.17 mm (0.007 inch) arranged according
to Figure 6. Hydraulic loading rates
should not exceed 28,080 m3/ha.d (3.0
mgad) and preferably should be in the
14,031 mS/ha-d (1.5 mgad) range
Using this criteria, filter run lengths
in excess of 131 days should be possible.
Filtration of Aerated
Lagoon Effluent
Bishop et al. (1976) conducted a
pilot scale single stage intermittent
sand filtration study to determine the
feasibility of upgrading aerated lagoon
effluent with intermittent sand filters.
The results of the study clearly indicate
that although BOD5 removal was accept-
able (i.e., effluent concentrations less
than 30.0 mg/1) suspended solids concen-
trations were not significantly reduced.
Thus, direct intermittent sand filtration
of aerated lagoon effluent does not
appear feasible.
The study (Bishop et al., 1976) also
investigated the single stage intermit-
tent sand filtration of a facultative
lagoon which was preceded by an aerated
lagoon. The results indicated that a
high quality effluent (less than 20 mg/1
BOD5 and SS) can be obtained. Thus,
aerated lagoon effluent may be upgraded
utilizing intermittent sand filtration
provided that the aerated lagoon is
followed by a facultative lagoon before
the effluent is applied to the intermit-
tent sand filtration.
mittent sand filtration of anaerobic
filter efn?ent iS not fusible. The
,«Hn efflu*nt BOD5 and suspended
solids concentrations were substantially
greater than 30.0 mg/1 in this study!
CASE STUDIES
Description
Three full scale lagoon-intermittent
sand filter systems have been studied for
three separate 30 day periods from
January 1977 to June 1978. The three
systems located at Mt. Shasta, Califor-
nia, Moriarty, New Mexico, and Alley,
Ueorgia, are shown schematically in
Figures 10, 11, and 12 and described in
Table 5.
Performance
A summary of the overall performance
of each system is reported in Table
6.
The BOD5 concentration of the three
systems is illustrated in Figures 13, 14,
and 15. At Mount Shasta, California, the
mean filter influent BOD5 concentration
was 22 mg/1 while the mean filter ef-
fluent BODg concentration was 11 mg/1
with a range of 2 mg/1. During Tour No.
1 (Mount Shasta) abnormally high filter
effluent 6005 concentrations are prob-
ably a result of short circuiting through
the filter caused by frozen filters and
excessively high hydraulic loading rates.
Proper filter operation will eliminate
problems due to freezing (Harris et al.
1977).
Intermittent Sand Filtration
of Anaerobic Lagoon Effluent
A laboratory scale study was con-
ducted to determine the feasibility
of intermittent sand filtration of
anaerobic lagoon effluent (Messinger
et al., 1977; Bishop et al., 1976). The
results indicated that direct inter-
At Moriarty, New Mexico, mean filter
effluent 8005 concentration? were 20
mg/1 and 21 mg/1 during Tours No. 1 and
3, respectively. However, during Tour
No. 2, the mean filter effluent BOD5
concentration was reduced to 10 mg/1.
This reduction was due to proper filter
maintenance and lower influent BODc
concentrations.
Table 5. Design criteria for full scale systems at Mount Shasta, California,
Moriarty, New Mexico, and Ailey, Georgia.
Parameter
Mount
Shasta
Moriarty
Alley
Design Q (mgd) 1.2
Lagoon Type Aerated
Filter Area (acre) 0.5
No. Filters 6
Hydraulic L.R. (mgad) 0.7
Effective Size (mm) 0.37
Uniformity Coeff. 5.1
0.4
Aerated/Facultative
0.082
8
0.6
0.20
4.1
0.08
Facultative
0.14
2
0.4
0.50
4.0
157
-------
At Alley, Georgia, the mean filter
effluent BODc concentration was 8 mg/1
with a range of 2 mg/1 to 22 mg/1. This
system produced a consistently high
quality effluent.
The suspended solids performance for
the three systems is illustrated in
Figures 16, 17, and 18. At Mount Shasta,
California, the three tours produced a
mean filter effluent suspended solids
concentration of 17 mg/1 with a range of
1 mg/1 to 49 mg/1. The high values are
associated with
problem.
the winter freezing
At Moriarty, New Mexico, the three
tour mean filter effluent suspended
solids concentration was 13 mg/1 with a
range of 2 mg/1 to 39 mg/1. The mean
filter influent suspended solids concen-
tration was 81 mg/1.
At Ailey, Georgia, the three tour
mean filter effluent suspended solids
concentration was 15 mg/1 with a range of
17
17
OPERATIONS
BUILDING
10
10
10
LEGEND
I BAR RACK
2 COMMINUTER
3 BYPASS BAR RACK
4 INFLUENT PARSHALL FLUME
5 PRIMARY AERATED LAGOONS
6 SECONDARY AERATED LAGOONS
7 LAGOON SYSTEM PARSHALL FLUME
8 BALLAST LAGOON
9
10
DOSING BASIN
INTERMITTENT SAND FILTERS
II CHLORINE CONTACT BASIN
12 EFFLUENT PARSHALL FLUME
13 RIVER DISCHARGE LINE
14 OUTFALL PUMP STATION
15 CHLORINATOR / SULFONATOR
16 AERATION BLOWERS
17 WATER RECLAMATION SYSTEM
Figure 10. Schematic of Mt. Shasta lagoon-intermittent sand filter system.
158
-------
1 nig/1 to 45 mg/1. The mean filter
influent suspended solids concentration
was 55 mg/1.
Operation and
Maintenance
Maintenance requirements for the
three sites were basically the same,
except for the increase in requirements
for the Mt. Shasta facility due to
its complex nature and larger size. Each
of the sites used the same basic pro-
cesses that required common routine
maintenance to provide a normal design
service life.
Table 7 presents a summary of the
reported maintenance requirements
for each of the three sites for a period
of approximately one year. The Moriarty,
New Mexico, and Ailey, Georgia, report is
the most complete and the most repre-
sentative of requirements for maintenance
of a lagoon-intermittent sand filter
system.
The Mt. Shasta facility was seem-
ingly plagued with problems either
induced or accidentally caused by the
operator. These problems many times
resulted in extensive repairs and in some
cases complete overhaul of portions
of the system. The aeration system at
Mt. Shasta also was a source of many
problems observed at the facility.
Constant operational changes and problems
in conjunction with the extensive main-
tenance activities have distorted the
reported maintenance requirements for the
Mt. Shasta facility.
In general, each of the three full
scale 1agoon-intermittent sand fil-
ter systems consistently produced an
effluent BOD5 and suspended solids
concentration of less than 30 mg/1.
Reported maintenance requirements
varied with the skill and ability of the
operator. However, operation and
maintenance of lagoon-intermittent sand
filter systems appears to be less
costly than constant systems.
(I IV
II
10*-
10 •»•
10 *-
10 *
(
o
0
o
o
1
i>
o
0
o
o
1
/
*-IO
*-IO
HHO
••10
LEGEND
I INFLUENT LIFT PUMP
2 CONTROL BUILDING
3 INFLUENT PARSHALL FLUME
4 COMMINUTER v-
5 PRIMARY AERATED LAGOONS
6 FLOW SPLITTER
7 SECONDARY FACULTATIVE LAGOONS
8 TABLET CHLORINATOR
9 DOSING BASIN WITH AUTOMATIC SYPHON
10 INTERMITTENT SAND FILTERS
II DISCHARGE OUTFALL LINE
O MANUAL VALVES
Figure 11. Schematic of Moriarty, New Mexico, lagoon-intermittent sand filter
system.
159
-------
Table 6. Summary of composite mean values for each sample point at each sample site during three tours.
Parameter
BOD (mg/1)
S. BOD (mg/1)
S.S. (mg/1)
V.S.S. (mg/1)
F.C. (col/lOOm)
I-pH (pH)
I-DO (mg/1)
COD (mg/1)
S. COD (mg/1)
Akl (mg/1
as CaC03)
TP (mg-P/1)
TKN (mg-N/1)
NH3(mg-N/l)
Org-N (mg-N/1)
N02 (mg-N/1)
N03 (mg-N/1)
Total Algal Count
(cells/ml)
Flow
Mt. Shasta Water Morlarty Wastewater Alley Sewage
Pollution Control Facility Treatment Facility Treatment Plant
Facility Lagoon Filter Facility Facility Lagoon Filter Facility Facility Lagoon Filter
Inf. Iff. Eff. Eff. Inf. Iff. Eff. Iff. Inf. Eff. Eff.
114
41
83
70
1.16xl06
6.9
4.8
244
159
95
4.68
15.5
10.8
4.8
0.16
0.28
N.A.
0.637
22
7
49
34
292
8.7
12.4
100
71
75
3.88
11.1
5.56
5.6
0.56
0.78
398022
N.A.
11
4
18
13
30
6.8
5.5
87
64
51
3.09
7.5
1.83
5.7
0.077
4.3
144189
N.A.
8
5
16
10
<2
6.6
5.3
68
50
42
2.72
5.2
1.76
3.4
0.020
4.5
141305
0.488
148
74
143
118
4.24xl06
8.0
1.8
305
197
436
10.3
60
38
22
0.05
0.05
N.A.
0.096
30
17
81
64
290
8.9
10.9
84
67
293
4.02
22
16
5.7
0.159
0.09
756681
N.A.
17
16
13
9
18
8.0
8.3
43
34
260
2.8
12.1
9.16
3.3
1.66
4.09
32417
0.046
17
16
13
9
34
8.0
8.3
43
34
260
2.8
12.1
9.16
3.3
1.66
4.09
32417
N.A.
67
17
109
87
2.17xl06
7.3
6.7
160
82
93
4.96
14.2
5.5
8.7
0.479
1.6
N.A.
N.A.
22
10
43
32
55
8.9
10.2
57
41
84
3.10
7.3
0.658
6.7
0.028
0.15
349175*
N.A.
8
6
15
8
8
7.1
7.4
32
23
76
2.67
4.1
0.402
3.8
0.073
2.36
21583*
N.A.
Facility
Eff.
6
5
13
6
<1
6.8
7.9
25
16
69
2.45
2.2
0.31
1.9
0.010
?.14
29360*
0.070
N.A. • Not Available
* = For Tours #1 and #2
-------
LEGEND
I INFLUENT MAIN LINE 6 LIFT STATION #2
2 LIFT STATION # I
3 FORCED MAIN
4 OXIDATION POND
5 FLOW SPLITTER
7 POLISHING POND
8 DOSING BASIN
9 INTERMITTENT SAND FILTERS
10 CHLORINE CONTACT CHAMBER
II IN-STREAM PARSHALL FLUME
12 SEWER RETURN LINE
13 CONTROL BUILDING
14 CONTACT CHAMBER DRAIN
LINE
Figure 12. Schematic of Alley, Georgia, lagoon-intermittent sand filter system.
50
H-0 -
30 -
^ 20 -j
O
DQ
10 -
+ TOUR NO. 1 C 1-22-77 TO 2-20-77)
X TOUR NO. 2 t 7-11-77 TO 8-20-77)
V TOR NO. 3 ( 4-If-78 TO f-38-78)
v v
1 ' ' ' I ' ' ' ' I
0 5 10
IS 20 25
TIME IN DRYS
30
T
va
Figure 13. Final effluent
SAMPLE POINT NO. 3
concentration at Mt. Shasta, California.
161
-------
75
o
CD
IS -
+ TOUR NO. 1 t S-19-77 TO 6-17-77)
X TOUR NO. 2 C 11-11-77 TO 12-13-77)
V TOUR NO. 3 ( S-lt-78 TO 3-15-78)
T~
IS
10
aa
as
313
TIME IN DRYS
SAMPLE POINT NO.4
Figure 14. Final effluent BOVc, concentration at Moriarty, New Mexico.
as -i
IS -
Q
CD
CD
10 -
S -
+ TOR NO. 1 (3-19-77 TO H-17-77)
X TOUR NO. a ( 9-16-77 TO 10-M-77)
V TCXfl ^D. 3 ( l-H-78 TO a-3-78)
10
15
32
TIME IN DRYS
SAMPLE POINT NO. 3
Figure 15. Final effluent 6005 concentration at Alley, Georgia.
162
-------
+ TOR NO. 1 f l-SS-77 TO 5-S3-77)
X TOR NO. 5 ( 7-H-77 TO 8-50-77)
TOUR NO. 3 ( H-1H--7B TO t-58-78)
cn
TIME IN DRYS
SAMPLE POINT NO. 3
Figure 16. Final effluent suspended solids concentration at Mt. Shasta, California.
S3S
cn
£00 -
175 -_
150 -_
ias -|
75 -
Figure 17.
+ TOUR NO. 1 ( 5-19-77 TO 6-17-77)
X TOUR ND. S t ll-lt-77 TO 12-13-77)
V TOUR NO. 3 (3-14-78 TO 3-15-78)
TIME IN DRYS
SAMPLE POINT N0.4
Final effluent suspended solids concentration at Moriarty, New Mexico.
163
-------
-I- TOUR NO. 1 ( 3-19-77 TO 4-17-77)
X TOUR NO. 2 ( 9-16-77 TO 10-W--77)
TOUR NO. 3 ( 1-1-78 TO a-E-78)
cn
0
0
TIME IN DRYS
SAMPLE POINT N0.3
Figure 18. Final effluent suspended solids concentration at Alley, Georgia.
Table 1. Summary of reported maintenance.
Job Description
Daily operation and
maintenance (daily
monitoring)
Filter cleaning
Filter raking
Filter weed control
Miscellaneous
maintenance
Grounds maintenance
Total reported
man-hours
Computed manpower
requirements
Actual reported
manpower input
Mount Shasta
WPCF
(1.0 hr) x 1
days x 52 wks =
365
54*
12 raking
16 mixing
N.A.
N.A.
42
489 plus man-hours
2.4 man-year**
2.0 man-years***
Moriarty
WWTF
(1.0 hr) x 7
days x 52 wks =
365
28*
13
None
11
8
425 man-hours
1 man-year**
0-28 man-year**
Alley
STP
(0.5 hr) x 5
days x 52 wks :
130
None
22
26
None
28
206 man-hours
1 man-year**
0.14 man-year**
* Man-hours with mechanical assistance
** Assuming 1500 man-hours = 1 man-year
*** Considering extra assistance for filter cleaning and weekend monitoring
164
-------
SUMMARY
Experimental research and practical
operation of full scale facilities
has demonstrated the effectiveness of
intermittent sand filtration for up-
grading lagoon effluents. As with all
wastewater treatment systems, perfor-
mance is limited by proper operation and
maintenance. However, less operator
skill and manpower is required for
operation of intermittent sand filters
than with most conventional systems.
Experience indicates that a high quality
effluent may be achieved at a relatively
low cost.
REFERENCES
Bishop, R. P., S. S. Messinger, E. J.
Middlebrooks, and J. H. Reynolds.
1976. Treating aerated and an-
aerobic lagoon effluents with
intermittent sand filtration. 31st
Purdue Industrial Waste Conference,
May 4-6. Purdue University, West
Lafayette, Indiana.
Fair, G. M., J. C. Geyer, and D. A. Okun.
19615. Water and wastewater en-
gineering, Vol. II. John Wiley &
Sons, Inc., New York, N.Y.
Harris, S. E., J. H. Reynolds, D. W.
Hill, D.S. Filip, and E.J. Middle-
brooks. 1975. Intermittent sand
filtration for upgrading waste
stabilization pond effluents.
Presented at 48th Water Pollution
Control Federation Conference,
Miami, Florida (October 5-10, 1975).
49 p.
Harris, S.E., D.S. Filip, J.H. Reynolds,
and E. J. Middlebrooks. 1977.
Separation of algal cells from
wastewater lagoon effluents. Vol.
I: Intermittent sand filtration to
upgrade waste stabilization lagoon
effluent. Final Report EPA Contract
No. 68-03-0281. Utah Water Research
Laboratory, Utah State University,
Logan, Utah.
Hill, D. W., J. H. Reynolds, D. S. Filip,
and E. J. Middlebrooks. 1977.
Series intermittent sand filtration
of wastewater lagoon effluents.
PRWR 153-1. Utah Water Research
Laboratory, Utah State University,
Logan, Utah.
Messinger, S. S., J. H. Reynolds, and E.
J. Middlebrooks. 1977. Anaerobic
lagoon - intermittent sand filter
system for the treatment of dairy
parlor wastes. Agricultural Experi-
ment Station, Utah State University,
Logan, Utah.
Reynolds, J. H., S. E. Harris, D. W.
Hill, D.S. Filip, and E.J. Middle-
brooks. 1974a. Single and multi-
state intermittent sand filtration
to upgrade .lagoon effluents. A
Preliminary Report, Presented at EPA
Technology Transfer Seminar on
Wastewater Lagoons, November 19-20,
Boise, Idaho.
Reynolds, J. H., S. E. Harris, D. W.
Hill, D.S. Filip, and E.J. Middle-
brooks. 1974b. Intermittent sand
filtration to upgrade lagoon ef-
fluents. Preliminary Report, p.
71-88. PRWG 159-1. Utah Water
Research Laboratory, Utah State
University, Logan, Utah.
Reynolds, J. H., S. E. Harris, D. W.
Hill, D.S. Filip, and E.J. Middle-
brooks. 1975. Intermittent sand
filtration for upgrading waste
stabilization ponds. In: Ponds as
a Wastewater Treatment Alternative.
Water Resources Symposium No. 9.
July 22-24, Center for Research in
Water Resources, University of
Texas, Austin, Texas.
Tupyi, B., D. S. Filip, J. H. Reynolds,
and E. J. Middlebrooks. 1977.
Separation of algal cells from
wastewater lagoon effluents. Vol.
II: Effect of sand size on the
performance of intermittent sand
filters. Final Report EPA Contract
No. 68-03-0281. Utah Water Research
Laboratory, Utah State University,
Logan, Utah.
165
-------
LAND APPLICATION OF LAGOON EFFLUENTS
A. T. Wallace*
INTRODUCTION
Beginning in the 1950s, many small
(and some not-so-smal1) communities
adopted wastewater lagoons in one form or
another in an attempt to meet treatment
requirements with minimum investments in
both capital construction and subsequent
operation and maintenance expense. Many
of these same communities, presented with
state and federal directives to improve
the quality of their lagoon effluents in
the 1970s, have turned to some form of
land application to avoid the obvious
problems associated with discharge
of nutrient and algae laden effluents to
small receiving streams Many other
communities, forced to abandon individ-
ual, on-site disposal or seeking less
costly, less complex treatment tech-
nology, have adopted combinations of
lagoons and land application of effluent.
In Idaho, for example, at least 15
federally funded projects involving the
lagoon-land application concept have been
approved and/or constructed since 1972.
These range in scale from about 20,000
gallons per day to 7 million gallons per
day. In addition, a few non-federally
funded projects of a similar nature have
been designed and built with state
approval. Based upon recent (June 1978)
telephone conversations with representa-
tives of design firms and regulatory
personnel, the situation is much the same
in the states bordering Idaho.
It should come as no surprise that
the reasons which lead to the selection
of lagoons over more expensive and
complex mechanical (either biological or
P/C) plants should be the same as those
for selecting land application over
alternate effluent upgrading technologies
in an over-whelming number of cases. Is
it not fatuous to select lagoons origi-
nally because of their simplicity, and
*A. T. Wallace is Professor, Civil
Engineering Department, University
of Idaho, Moscow, Idaho.
then proceed to upgrade them by tacking
on a complete water filtration plant?
LITERATURE REVIEW
A review of the literature reveals
that there are a great number of lagoon-
land disposal systems throughout the
U.S.
In EPA's "Survey of Facilities Using
Land Application of Wastewater" a
mail survey was conducted throughout the
U.S. to gather information about com-
munities using land application as a
means of treatment or effluent disposal.
Of 67 communities which responded,
acknowledging their use of land applica-
tion, 27 (40%) were employing lagoons as
the method of preapplication treatment,
37 communities (including some of those
using lagoons) reported the use of
wastewater "holding ponds" varying in
size from (V/Q) 5 days to over 30 days.
One would certainly expect that effluent
from such "holding ponds" would corres-
pond closely in character to that from
ponds designed specifically as treatment
lagoons.
Some of these systems dated back to
the early 1900s (one to 1889) and
have been in continuous use. Most of the
systems were subsequently visited
by one of four project field investi-
gators and very few problems are mention-
ed in their written commentary. In a few
cases, the only problem mentioned
was lack of suitable land to expand the
system. As most of the systems reported
on were in arid western states (Califor-
nia, Oregon, Washington, Arizona, and
Texas accounted for most of them) it is
not hard to understand why trouble-free
operation prevails. In most instances
the water would be of considerable value
to the operator of the land disposal
portion of the system. Thus, he could be
expected to give immediate attention to
any problem areas, such as odors or
insects, so as not to jeopardize his
rights to use the effluent.
166
-------
Unfortunately, reasonably good data
on design and operation, especially
with regard to process performance, are
quite scarce. As many of the systems
are very small and probably never moni-
tored, this is not surprising. All
but a very few of the land application
portions of these systems are operated
at low hydraulic rates, with application
only to vegetated areas during the
growing season. For these systems at
least, adverse impacts are minimal
and the owners have been largely relieved
of the responsibility for extensive
monitoring.
It is of interest to note that for
low rate systems utilized only during
the growing season with harvest of the
crop practiced, that no definitive
record of adverse impact to either soil
or groundwater could be found in the
literature search. Steel and Berg (1954)
for example, concluded that the rela-
tively minor changes produced in soils
irrigated with effluents were neither
especially beneficial nor injurious to
the soil. Slight increases in organic
matter were to be expected, together with
increases in pore space and an improve-
ment in crumb structure. These changes,
which would be considered improvements,
are off-set by a slight build-up in the
salt content of the soil solution. It
can be presumed that proper management
techniques will allow indefinite use of
low rate wastewater irrigation systems
which apply lagoon effluents of reason-
ably good quality.
Malhotra and Myers (1975) reported
some data on groundwater quality beneath
and adjacent to the land disposal area of
two combination lagoon-land application
areas. Increases above background were
observed for chloride, nitrate, specific
conductance, and alkalinity. However,
the increases were tolerable relative to
water quality criteria for most pur-
poses. Increases were higher for higher
hydraulic loadings and also for sandier
soils.
Hicken et al. (1978) performed a
2-year field study using three dif-
ferent application rates (2, 4, and 6
inches per week) on four different
soil types, ranging from a clay to a
sandy loam texture. Increases in
specific conductance and sodium in the
percolate were high enough to prevent
additional reuse of the drainage water
for irrigation. Increases in nitrate
and organic carbon were also observed,
however, it was concluded that these
increases were primarily caused by
leaching of nitrates and carbon which
were present in the soil prior to the
initiation of irrigation with lagoon
effluent.
systems, the situa-
different. These are still
as opposed to
Relative to high rate (for example,
rapid infiltration)
tion is quite
t rjscit, merit , as opposed to a. 1,
systems although they have been referred
to otherwise by some engineers. However,
because of the heavier hydraulic (con-
comitantly all constituent) loadings,
they have a greater impact on both soil
and groundwater. Bouwer (1978) has
suggested that such systems only be
allowed when groundwater quality is
either of no consequence or when the
percolate can be controlled (as
recharge or pumping). Their
discouraged in some states,
Michigan (Malhotra and
by stream
use has been
for example
Myers, 1975).
An interesting observation was made
by Bouwer relative to the effect of
algae in the clogging process in rapid
infiltration systems. The data accumu-
lated so far at Flushing Meadows (Phoe-
nix) seem to indicate that algae have a
greater clogging potential than an equal
mass of suspended solids from secondary
treatment (activated sludge) at the high
loading rates employed in that system
(over 45 inches/week). This fact is
ordinarily of no consequence for the more
common low-rate systems (around 1 to 3
inches/week). However, Hicken et al.
(1978) observed prolific algae growths on
nonvegetated control plots at application
rates of 2 to 6 inches per week. Con-
trary to Bouwer's observations, they
concluded that the algae mats did not
increase the hydraulic impedance on these
sites. Perhaps the explanation lies in
the great difference in application rate
between the two sets of observations.
A REVIEW OF TWO INTERESTING PROJECTS
Davis, California
The background work leading to the
upgrading of the Davis, California,
lagoon system is described by Tucker et
al. (1977). The present system consists
of a complete battery of preliminary and
primary treatment units. These include
coarse screening, prechlorination ,
comminution, pre-aeration/ grit removal,
and primary sedimentation. These units
are credited with 35 percent removal of
BOD and 65 percent removal of suspended
solids. The next stage of treatment
consists of three facultative ponds
operated in parallel. The detention time
is 39 days based on an inflow of 5 mgd.
Recirculation is provided via two high
flow (15 mgd), low head pumps and re-
circulation channels. A recirculation
ratio of 0, 3, or 6 can be provided.
Through 1975, the city met all
Regional Water Quality Board discharge
requirements except that for suspended
167
-------
solids. The target level was 30 mg/1
and their 1975 average was 74 mg/1 with
the highest monthly average recorded
as 93 mg/1. Interestingly, the lagoon
flow scheme was modified from parallel
to series operation for a few months to
try to reduce effluent suspended solids
with no apparent success.
Alternatives which received con-
sideration included replacement of
the existing lagoons as well as lagoon
effluent treatment. Table 1 summarizes
the costs of the three lagoon effluent
upgrading options for Davis.
On an annual cost basis, assuming a
20 year life for physical improve-
ments and a 7 percent interest rate, the
overland flow scheme shows the least
cost. Although only the assumed cost of
the land ($360,000) was included in
the salvage value of the project, at
least a portion of some of the improve-
ments (terrace construction and distribu-
tion system) which might make the
property more valuable to a subsequent
agricultural operator might have been
included as well. In addition, no income
from the harvest of grass hay was
included. Both of these factors would
tend to make the overland flow option
even more attractive.
In terms of environmental impact, a
positive benefit was assumed due to
the increase in wildlife habitat. The
negative aspects of enhanced insect
breeding would have to be solved by
careful design and management.
A 5-month pilot scale program was
undertaken on three 50 ft by 100 ft
plots seeded with annual rye grass. The
slope of the plots was 2 percent.
Data collection spanned the period from
11 November 1975 to 27 March 1976.
From this program, the maximum practical
hydraulic loading was identified as
1.2 inches per day. Beyond this loading,
effluent (runoff) quality became margin-
ally acceptable. As the grass was
observed to grow continuously during
this period, it was concluded that
year-around operation may be feasible
in this climatic area.
Muskegon County (Michigan)
No treatment of this subject would
be complete without mention of this
immense project. A complete description
is available (Demirjian, 1975) and
only the highlights are summarized in the
following paragraphs.
The system is located on 11,000
acres of formerly unproductive sandy
land. The total design capacity is 42
mgd of combined domestic-industrial
waste. Biological treatment is provided
by three aerated lagoons, operated
in either series or parallel, with a
detention period of 3 days. Two storage
lagoons provide approximately 4 months of
storage at the design flow.
Effluent may be taken from storage
or directly from the aerated lagoons
via a small settling pond, chlorinated
and applied to the land. The irri-
gation system employs center pivot
machines of special design and covers
6,000 acres. The water budget calls for
an application of 3.8 inches per week
(including precipitation) for an 8 month
irrigation season. Field (feed) corn is
the primary crop.
An important aspect of the Muskegon
system is the control of subsurface
water and percolate. An extensive
drainage system, utilizing tiles, wells,
and ditches, was required to control the
groundwater table and prevent waterlog-
ging in the aerobic (renovation) zone.
Table 1. Capital and O&M costs for
lagoon effluent upgrading
options for Davis, California.
(September 1977 Construction
Costs ENRCCI - 3200.)
Option
Capital Cost Annual O&M
Coagulation-
Flocculation-
Sedimentation
Intermittent
Sand Filtration
Overland Flow
$1.51 mill
$3.52 mill
$1.98 mill
$278,000
$ 79,000
$ 88,000
Because of the size of the project
and some of its political ramifications,
a rather large sum of money has been
allocated for its study. Thus, in con-
trast to many of its lesser (in scope)
counterparts, a great deal of performance
data is being accumulated for the Muske-
gon system. Some of the most important
findings to date are: 1) No significant
accumulations of most heavy metals
observed in either grain or plant tissue.
Cd and Zn concentrations increased in the
tissue but not in the grain. 2) The
nitrogen content of the wastewater was
insufficient to support optimum corn
growth, thus had to be supplemented.
Application of the optimum amount of
nitrogen resulted in a decrease i n
nitrogen lost in the percolate. 3)
168
-------
Excellent performance is being experi-
enced relative to organic removals
through the land application portion of
the system. The same is true for nitro-
gen forms and phosphorus. 4) Bacterial
quality of the percolate, however, has
been erratic and often above the adopted
levels (200 fecal eoliform per 100
ml) .
In summary, the Muskegon County
system must be viewed as a very success-
ful example of the technology which we
are discussing. This in spite of
severe problems encountered with the
system hardware during start-up and
a very shakey first season of operation.
The system is a unique example of
land application of lagoon effluent on a
grand scale and for a few years had
produced two polarized camps; one of
ardent supporters and one of equally
ardent opponents. The fact that one
seldom hears vicious attacks on the
system in public anymore is probably
significant.
OBSERVED PLANNING AND
DESIGN DEFICIENCIES
A total of 16 projects utilizing a
combination of lagoons and land applica-
tion were carefully reviewed in the
preparation of this paper. Of these
projects, 12 were located in Idaho, 2 in
Wyoming, and 2 in Oregon. The preliminary
plans (now called "facilities plans") for
these projects cover a period from 1971
to 1978. Thus they should (and do)
reflect both improvements in the state-
of-art and tightening requirements by the
state regulatory agencies and the EPA
relative to land application. For
example, plans prepared during the years
1971-1973 contain very little of the
site-specific data (climate, geology,
groundwater, and soils) which are rou-
tinely found in more recent reports.
However, even among these later, more
detailed, reports there is a wide diver-
gence in the general approach. Much
important information seems to be left
out in some plans. Significant design
parameters are developed by many, often
widely different, techniques in others.
Design parameters are often assumed
without benefit of site work in some
plans and these same parameters are
derived from field measurements in others
without specifying the methods used,
tabulating the raw data, or showing the
calculated statistics of the measure-
ments. Incorrect calculations were
observed in a few cases. In another
few cases, seemingly representative and
consistent data were obtained and pro-
perly analyzed, but subsequent design
loadings were chosen which bore no
apparent relationship to the derived
quantity or quantities. The inconsis-
tency in basic assumptions, particularly
with regard to nitrogen balances, was the
most puzzling observation. In addition,
assumptions which were obviously derived
from literature searches were neither
consistent (from one firm to the next)
nor properly referenced.
Many of these deficiencies could
have been corrected by faithfully
following a comprehensive set of guide-
lines, for example, ADDENDUM NO. 2
to Recommended Standards for Sewage Works
(1968 Edition), Great Lakes - Upper
Mississippi Board, "Ground Disposal of
Wastewaters" available as of April 1971.
A more recent, and much more detailed,
guidance document has been made available
through the EPA (Oct. 1977).
In summary, the person(s) preparing
the plans reviewed, with a few notable
exceptions, seemed to be quite comfort-
able with all aspects of the analysis
except that dealing with the land appli-
cation portion.
This observation extends to the
important relationship between the
lagoon effluent quality and the land
application portion of the project.
Lagoon sizing criteria were quite arbi-
trary and in no way related to the
ability of a particular soil to accept
effluent, or to a desired endpoint,
for example, a given groundwater quality.
The relationship depicted by Figure 1 was
not considered, even in a gross way,
during any of the planning efforts in
hopes of identifying a truly least-cost
system. However, in fairness to the
engineering firms, it should be pointed
out that state regulations, at least in
Idaho and Oregon, force the system
configuration toward the left side of the
graph, thus ruling out any possibility
of achieving a cost-effective solution.
At present, only 26 states have
regulations (or guidelines) pertaining
to land application of wastewaters. Of
these, 21 require secondary treat-
ment as the minimum level of pre-treat-
ment. It is plain that where direct
discharge of effluents would be allowed,
land application will never be part of a
cost-effective solution for these
states.
21
There are a lot of unanswered
questions relative to the fate of specif-
ic constituents in the soil and ground-
water (not to mention aerosols from
spray operations). Certainly we need to
make efforts to fill these gaps in
our knowledge. (See, for example refer-
ences 10 and 11.) However, many of
169
-------
CO
O
O
z
LJ
CO
LL)
LAND APPLICATION
SYSTEM
PERCENT OF A LIMITING CONSTITUENT TO BE
APPLIED TO THE LAND
(AFTER : M.R. OVERCASH, ETAL, INDUSTRIAL WASTE LAND
APPLICATION. AICHE TODAY SERIES 1976)
the same questions exist relative to the
fate of pollutants discharged to surface
waters. We can't afford to cease either
method of disposal while we wait for
every last question to receive a satis-
factory answer. There are sonie (Bern-
arde, 1973) who are of the opinion that
land disposal is potentially far less
hazardous, from the standpoint of com-
municable disease transmission, than
disposal into rivers and streams.
As in many fields of technology, we
are forced to "refine as we go"; making
some mistakes and learning from them,
then incorporating what we have learned
into the next system. In the meanwhile,
we must change the way in which we think
about some of the impacts. Phelps, in
1944, decried the enactment of laws
"calling for a given standard of treat-
ment regardless of the character or
use of the stream." He espoused tailor-
ing design of treatment works to protect
all beneficial uses of the receiving
stream while utilizing the assimilative
capacity to the maximum extent consistent
with the preservation objective. I
believe that Phelps was right in 1944 and
he is still right. Also, his philosophy
applies equally well to land application
systems. Regulatory agencies have
recognized the necessity of establishing
a "mixing zone" next to outfalls, within
which water quality standards do not
apply as strictly as they do beyond
the mixing zone. Why then do we have so
much concern for groundwater quality
directly below the land application
site? Emrich (1978) has suggested
general adoption of a concept analogous
to the "mixing zone" for evaluating land
application systems and a similar concept
has already been applied (Wallace,
1973).
SUMMARY REMARKS
When considering land application as
a technique for upgrading lagoon ef-
fluents, there is no reason to allow your
thinking to be too narrowly constrained.
For example, some states do not allow
land application outside of the period
which normally constitutes the "growing
season." If strict control of nitrogen
in the groundwater has been identified as
a critical system requirement, there is
good reason for limiting the period of
irrigation. However, when nitrogen
considerations are not important, why
limit the period for application? Surely
BOD, suspended solids, phosphorus and
many other constituents will be trans-
formed or removed during the cold
weather if there are no physical limita-
tions to applying wastewater. Al-
though ice formation has restricted
application for some systems (Armstrong,
170
-------
Borrelli and Burman, 1978), by careful
design and management others have
operated successfully at temperatures
down to -35°F (Anderson, 1975).
The spray system at Thayne, Wyoming,
discussed by Armstrong et al. was
modified to employ rapid infiltration
during the coldest part of the winter
to avoid the problems caused by ice
formation around the sprinkler heads
(Orton, 1978). This technique would
prove useful at many locations to
avoid the high cost of long-term effluent
storage. In addition, rapid infiltration
or flood irrigation might easily be used
in a portion of the buffer areas pre-
scribed by regulatory agencies around
spray fields to promote more efficient
use of the land.
Other possibilities for the use of
innovative technology would involve
the use of artificial marshes, after the
lagoon system, but prior to land applica-
tion. Such a scheme might be used when
increased nutrient or algae removal
became necessary.
It seems certain that a great number
of lagoon systems will be upgraded
through the use of land application of
effluents and many lagoon-land ap-
plication systems will be designed and
built as integrated units for the
purposes of fostering nutrient recycle.
The land application portion of these
systems will ordinarily be considered as
innovative or alternative technology,
thereby qualifying these subsystems for
an additional 10 percent federal funding.
In response to this, design firms will
gradually develop the expertise necessary
to plan and design these systems for
maximum public benefit and minimum
adverse impact.
REFERENCES
1. Sullivan, R. H., M. M. Cohn, and S.
S. Baxter. July 1973- Survey
of Facilities Using Land Application
of Wastewater. Office of Water
Programs Operations, U.S. Environ-
mental Protection Agency, Washing-
ton, D.C. 377 p-
2. Steel, W., and E. J. M. Berg.
November 1954. Effect of Sewage
Irrigation upon Soils. Sewage and
Industrial Wastes. 26:1325-39.
3. Malhotra, S. K., and E. A. Myers.
November 1975. Design, Operation
and Monitoring of Municipal Irriga-
tion Systems. Jour. Wat. Poll.
Con. Fed. 47:2627-39.
10.
11
13.
14.
Hicken, B. T. , et al. 1 977 .
Separation of Algae Cells from
Wastewater Lagoon Effluents. Vol.
Ill: Soil Mantle Treatment of
Wastewater Stabilization Pond
Effluent - Sprinkler Irrigation.
Municipal Environmental Research
Laboratory, U.S. Environmental
Protection Agency, Cincinnati, Ohio.
218 p.
Bouwer, H.
munication.
1978. Personal corn-
Tucker, D. L., et al. January 1977.
Overland Flow of Oxidation Pond
Effluent at Davis, California.
USEPA Technology Transfer Program.
25 p.
Demirjian, Y. A. October 1975.
Muskegon County Wastewater Manage-
ment System. USEPA Technology
Transfer Program. 91 p.
Great Lakes - Upper Mississippi
Board. April 1971. Addendum No. 2
to Recommended Standards for Sewage
Works - Ground Disposal of Waste-
waters. 4 p.
Process Design Manual for Land
Treatment of Municipal Wastewater.
October 1977. U.S. Environmental
Protection Agency, Environmental
Research Information Center, Office
of Water Program Operations.
Adriano, D. C., et al. 1975.
Effect of Long Term Land Disposal
by Spray Irrigation of Food Pro-
cessing Wastes on Some Chemical
Properties of the Soil and Subsur-
face Water. Journal Environmental
Quality, 4-242-48.
Gerba, C. P., C. Wallis, and J. L.
Melnick. September 1975. Fate
of Wastewater Bacteria and Viruses
in Soil. Proc. ASCE 101 Jour, of
the Irrigation and Drainage Division
No. IR3:157-75.
Bernarde, M. A. 1973- Land Dis-
posal and Sewage Effluent: Ap-
praisal of Health Effects of Patho-
genic Organisms. Jour. AWWA 65:
432-40.
Phelps, E. B. 1944. Stream Sanita-
tion. John Wiaey and Sons, Inc.,
New York. p. 187.
Emrich, G. H. March 1978. Formu-
lating Public Policy on Land Appli-
cation of Wastewater and Residuals.
Water and Sewage Works 125:78-81.
171
-------
15. Wallace, A. T. 1973. Subsurface
Disposal of Filtered Secondary
Effluent at Woodside Subdivision -
Hailey, Idaho. (with one addendum).
Report to Tri-Co. Development Corp.,
Elko, Nevada. 47 p.
17. Anderson, D. R., Rogers Brothers
Co., Inc., Idaho Falls, Idaho.
Personal communication.
18. Orton, R. ¥., Tudor Engineering Co.,
Boise, Idaho, Personal communica-
tion.
Armstrong, D. L., J. Borrelli, and
R. D. Burman. February 1978.
Land Application of Wastewater for
Treatment and Disposal: The Thayne,
Wyoming Experience. Presented at
the Rocky Mountain Regional Meeting,
American Society of Agricultural
Engineers, Denver. 14 p.
ACKNOWLEDGMENTS
The author wishes to express his
appreciation to individuals of the
U.S. Environmental Protection Agency
(Idaho Operations Office), Idaho Depart-
ment of Health and Welfare and several
consulting firms who provided access to
copies of their reports and plans.
172
-------
DISINFECTION OF LAGOON EFFLUENTS
Bruce A. Johnson*
For many years, wastewater stabili-
zation ponds have been used success-
fully in all parts of the United States
to provide treatment of domestic and
industrial wastes. Since ponds require
very little operator control and main-
tenance for successful performance, they
have been particularly popular among
small and rural communities, where land
is relatively inexpensive. However, as
the result of more stringent state and
federal discharge standards, many pond
systems are unable to meet new require-
ments. This is particularly true with
respect to bacterial reduction. There-
fore, disinfection must be considered as
a means of upgrading pond effluent to
meet bacteriological discharge standards.
LITERATURE REVIEW—CHLORINATION
OF POND EFFLUENT
Since chlorine, at present, is less
expensive and offers more flexibility
than other means of disinfection, chlori-
nation, is the most practical method of
reducing bacterial populations. However,
there is evidence that chlorination of
wastewater high in organic nitrogen
content, such as stabilization pond
effluent, may be accompanied by adverse
effects. Therefore, several major
research projects have been undertaken in
recent years to investigate the chlori-
nation of pond effluents.
White (1973) has suggested that
chlorine demand is increased by high
concentrations of algae commonly found in
pond effluents. It was found that
to satisfy chlorine demand and to produce
enough residual to effectively dis-
infect algae laden wastewater within
30-45 minutes, a chlorine dose of 20-30
mg/1 was required. Kott (1971) also
reported increases in chlorine demand
as a result of algae, but found that a
*Bruce A. Johnson is PhD, PE Fors-
gren, Perkins & Associates, P.A., Rex-
burg, Idaho.
chlorine dose of 8 mg/1 was sufficient
to produce adequate disinfection within
30 minutes and that if contact times
are kept relatively short, no serious
chlorine demand by algae cells is encoun-
tered. Of course, the amount of chlorine
demand exerted is highly variable.
Dinges and Rust (1969) found that for
pond effluents, a chlorine demand of
only 2.65 to 3.0 mg/1 was exerted after
20 minutes of contact. Brinkhead and
O'Brien (1973) found that at low doses of
chlorine, very little increase in chlo-
rine demand is attributable to algae,
but at higher doses, the destruction of
algae cells greatly increases demand.
This is because dissolved organic com-
pounds released from destroyed algae
cells, as explained by Echelberger et al.
(1971), are oxidized by chlorine and thus
increase chlorine demand.
Another concern regarding the
chlorination of pond effluents is the
effects on biochemical oxygen demand
(BODc;) and chemical oxygen demand (COD)
Brinkhead and O'Brien (1973) and Echel-
berger et al. (1971) found that for
higher chlorine doses, increases in
BODc, due to destruction of algae cells
were observed. Echelberger et al. (1971)
also reported increases in soluble COD.
Horn (1972) found that when 2.0 mg/1
chlorine was applied to pond effluent,
the BODc; measured was 20 mg/1. How-
ever, when 64 mg/1 chlorine was applied,
the BODc increased to 129 mg/1. How-
ever, Zaloum and Murphy (1974) observed a
40 percent reduction of BODc; resulting
from chlorination. Dinges and Rust
(1969) also reported reductions of
BOD5. Kott (1971) has suggested that
increases in 8005 may be controlled by
using fairly low chlorine doses coupled
with relatively long contact periods.
The formation of toxic chloramines
is also of concern in chlorinating
pond effluents. These compounds are
found in waters high in ammonia concen-
tration and are extremely toxic to
aquatic life found in receiving water.
For example, Zillich (1972) has deter-
mined that a chloramine concentration
of 0.06 mg/1 is lethal to trout.
173
-------
Not all of the side effects of
chlorinating pond effluents are detri-
mental. Kott (1973) observed reductions
of suspended solids (SS) as a result of
chlorination. Dinges and Rust (1969)
reported reductions of volatile suspended
solids (VSS) by as much as 52.3 percent
and improved water clarity (turbidity) by
31.8 percent following chlorination.
Echelberger et al. (1971) reported that
chlorine enhances the flocculation of
algae masses by causing algae cells to
clump together.
Additional research has been and is
being conducted regarding improve-
ment of chlorination efficiency, and
chlorine contact tank design for waste-
water treatment in general. Additional
research, however, directed speci-
fically to chlorination of pond ef-
fluents, is needed to more fully under-
stand control and design parameters for
this application of chlorination.
BASIC PRINCIPLES OF
CHLORINATION
To understand the effects of chlori-
nating stabilization pond effluents,
it is necessary to review the basic
principles of chlorination. When chlo-
rine gas is used the gas reacts with
water to form hypochlorous acid (HOC1).
In a pure water system, the reaction is
as follows:
4-
-HOC1 + H + CL
(1)
The hypochlorous acid then dissassociates
to form OC1- and H+
HOC1
• H
OC1"
(2)
When Ca(OCl)2> for example, is used to
chlorinate, OC1~ is formed by the follow-
ing reaction:
Ca(OCl)2 —- Ca + 20C1"
. (3)
The OC1~ is then free to form hypo-
chlorous acid in contact with hydro-
gen ions. Chlorine in the form of HOC1
or OCL- is referred to as free chlo-
rine. Both forms of free chlorine are
powerful disinfectants and react quickly
to destroy bacteria and most viruses.
In wastewater, such as stabilization
pond effluents, various chemical com-
ponents react with free chlorine to form
compounds which are ineffective as
disinfectants. That is, the rates of
reactions between chlorine and these
components are faster than the rate at
which chlorine attacks and kills bacteria
and viruses. Fe"1"1", Mn"1"1", N02~ and
S= are common reducing agents which
combine readily with chlorine to prevent
it from disinfecting. A typical reaction
is as follows:
H2S
4C1
4H20
8HC1
(4)
Free chlorine also reacts with
ammonia found in wastewater to form a
series of compounds known as chloramines.
Although chloramines are less than
5 percent as efficient as free chlorine
in destroying bacteria and viruses,
they do play an important role in dis-
infection because they are fairly stable
and can continue to provide disinfection
for some time after application. The
common forms of chloramines, or combined
chlorine, as they are referred to, are
monochloramine, d ichloramine, and nitro-
gen trichloride. The reactions for their
formation are as follows:
NH3+HOC1 —
NH2C1 + HOC1
NH2C1
*• NHC1
HOC1 ;rr
. (5)
. (6)
. (7)
In some cases, chlorination is used
as a treatment step to drive off un-
desirable ammonia. This is known as
breakpoint chlorination. Basically,
chlorine is added until all the chlorine
has reacted to form chloramines. With the
addition of more chlorine, the ammonia is
converted to nitrogen gas and driven off.
Any additional chlorine added beyond that
point is maintained in solution as free
chlorine residual. The mechanisms
involved are fairly complex, but the
overall reaction may be represented as
follows:
2NH,+ 3HOC1•
3HC1
(8)
A comparison of ideal breakpoint
chlorination versus wastewater break-
point chlorination is represented in
Figure 1. Because the chlorine dose
necessary to reach the breakpoint in
wastewater is much higher than the
dose necessary to achieve adequate
disinfection, breakpoint chlorination is
seldom used in the treatment of waste-
water .
FIELD STUDY--CHLORINATION OF POND
EFFLUENT
To add to the knowledge concerning
the chlorination of pond effluents,
a study was conducted during 1975-76 at
Utah State University to evaluate pond
chlorination practices and facilities
under varying seasonal conditions.
The experimental chlorination facilities
174
-------
were constructed with the capabilities
of treating either primary or secondary
pond effluent. Four systems of iden-
tically designed chlorine mixing and
contact tanks, each capable of treating
50,000 gallons per day, were constructed
Three of the four chlorination systems
were used for directly treating pond
effluent. The effluent treated in the
fourth system was filtered through an
intermittent sand filter prior to chlori-
nation to remove algae. The filtered
effluent was also used as the solution
water for all four chlorination systems.
An overall schematic of the chlorination
system is illustrated in Figure 2.
Following recommendations by
Collins, Selleck, and White (1971),
Kothandaraman and Evans (1972 and 1974)
Wdstewater Breakpoint Curve
ui
2
cc
o
i
o
Q
CO
LU
CC
Applied Dose
Free
Chlorine
Combined Chlorine
APPLIED CHLORINE
Ideal Breakpoint Curve
LU
Z
CC
o
I
o
Q
CO
LU
CC
Applied Dose
Free
Chlorine
APPLIED CHLORINE
Figure 1. Comparison between ideal and
wastewater chlorination curves,
and Marske and Boyle (1973), the chlori-
nation systems were constructed to
provide rapid initial mixing follow-
ed by chlorine contact in plug flow
reactors. A serpentine flow configura-
tion having a length to width ratio of
25:1, coupled with inlet and outlet
baffles, was used to enhance plug flow
hydraulic performance. The chlorine
mixing and contact tanks are illustrated
in Figure 3. The maximum theoreti-
cal detention time for each tank was 60
minutes, while the maximum actual
detention time averaged about 50 minutes.
The pond effluent was chlorinated at
doses ranging from 0.25 to 30.0 mg/1
under a variety of contact times, temper-
atures, and seasonal effluent conditions
from August 1975 to August 1976. A
variety of chemical, physical, and
bacteriological parameters were monitored
during this period in evaluating the
chlorination of pond effluents. A series
of laboratory experiments as also con-
ducted to compliment the field study.
Some of the major findings of this study
are summarized as follows:
1. Sulfide, produced as a result of
anaerobic conditions in the ponds
during winter months when the ponds are
frozen over, exerts a significant
chlorine demand. This is illustrated in
Figure 4. For sulfide concentrations of
1.0 - 1.8 mg/1, a chlorine dose of 6 to 7
mg/1 was required to produce the same
residual as a chlorine dose of about 1
mg/1 for conditions of no sulfide.
2. For all concentrations of
ammonia encountered, it was found that
adequate disinfection could be obtained
with combined chlorine residual in
50 minutes or less of contact time.
Therefore, breakpoint chlorination,
and the subsequent production of free
chlorine residual, was found to be
rarely, if ever, necessary in disin-
fecting pond effluent.
3. In considering the chlorination
of pond effluents, concern has been
expressed that the lysis of algae cells
would cause an increase in chemical
oxygen demand (COD). It was found that
total COD is virtually unaffected by
chlorination. Soluble COD, however, was
found to increase with increasing
concentrations of free chlorine only.
This increase was attributed to the
oxidation of suspended solids by free
chlorine- Increases in soluble COD
versus free chlorine residual are illus-
trated in Figure 5.
4. Some reduction of suspended
solids, due to the break down and oxida-
tion of suspended particulates, and
resulting increases in turbidity were
175
-------
INFLUENT
CHLORINE
SOLUTION
INFLUENT
PLAN VIEW
EFFLUENT
ij
-*~j-w~~.
)
)RINE
JTION
O O O
0 0
o o o
o o o
0 0
o o o
o o
o o o
ELEVATION
Figure 2. Experimental chlorination schematic.
Figure 3. Chlorine mixing and contact tanks.
-------
15
o>
E
o
to 10
IU
oc
ui
2
CE
O
_J
1 *>
O °
o
h-
0
RESIDUAL = 1.552 * 0.346 (DOSE)
R = 0.956
20
u 5 10 15
CHLORINE DOSE (mg/l)
Figure 4. Chlorine dose vs. residual for initial sulfide concentrations of 1.0 - 1.8 mg/l.
EQUATION OF LINE
Y = 4.692X-2.948
01 2345
FREE CHLORINE RESIDUAL (mg/l)
Figure 5. Changes in soluble COD vs. free chlorine residual--unfiltered lagoon effluent.
177
-------
attributed to chlorination . However,
this reduction was found to be of
limited importance in comparison with
reductions of suspended solids result-
ing from settling. Suspended solids were
found to be reduced by 10-50 percent
from settling in the contact tanks.
5. Filtered pond effluent was found
to exert a lower chlorine demand than
unfiltered pond effluent, due to the
removal of algae. This is comparatively
illustrated in Figure 6. The rate of
exertion of chlorine demand was deter-
mined to be directly related to chlorine
dose and total chemical oxygen demand.
6. A summary of coliform removal
efficiencies as a function of total
chlorine residual for filtered and
unfiltered effluent is illustrated
in Figure 7. It was found that the rate
of disinfection is a function of the
chlorine dose and bacterial concentra-
tion. Generally, the chlorine demand
was found to be about 50 percent of the
applied chlorine dose except during
periods of sulfide production.
7. Disinfection efficiency was
found to be highly temperature depen-
dent. At colder temperatures, the
reduction in the rate of disinfection
was partially offset by reductions in the
exertion of chlorine demand. However,
the net effect was a reduction in the
chlorine residual necessary to achieve
adequate disinfection with increasing
temperature for a specific contact
period.
8. In almost all cases, adequate
disinfection was obtained with com-
bined chlorine residuals of between 0.5
and 1.0 mg/1 after a contact period
of approximately 50 minutes. This
indicated that disinfection can be
achieved without discharging excessive
concentrations of toxic chlorine re-
siduals into receiving waters. Also, it
was found that adequate bacterial
removal can be achieved with relatively
low doses of applied chlorine during
most of the year.
DESIGN CRITERIA
The objective of chlorinating pond
effluents is to reduce bacterial popula-
tions to acceptable levels while mini-
mizing the applied chlorine dose required
and any adverse effects which might be
imparted to receiving waters. Typically,
fecal coliform bacteria must be reduced
to less than 200/100 ml on a daily
average. To accomplish this objective,
careful attention must be given to design
and operation of chlorination facilities,
particularly with respect to mixing and
hydraulic performance of the contact
chambers. A summary of some major design
criteria is contained in the following
sections.
Mixing
Rapid, initial mixing is probably
the most important aspect of efficient
disinfection and should be accomplished
within about 5 seconds and prior to
entering a contact chamber. Several
methods of mixing are:
1. Hydraulic jump. This is prob-
ably the best method for obtain-
ing rapid mixing in an open
channel.
2. Mechanical mixers. The mixer
should be located immediately
downstream from the point of
chlorine injection and the
mixing chamber should be as
small as possible.
3. Turbulent flow through restrict-
ed reactor. This is a highly
effective method in most cases,
particularly in a closed con-
duit.
4. Injections of chlorine into full
flowing pipe. Probably the
least efficient method and
should not be used in pipes 30
inches in diameter and larger.
Contact Chambers
Chlorine contact chambers should be
designed to provide at least 1 hour
detention time at average flow and 30
minutes detention time at peak hourly
flow, whichever is greater.
1. Hydraulic performances. Ide-
ally, contact tanks should be
designed to produce near ideal
plugflow. Hydraulic conditions
may be considered acceptable
when the modal value, as deter-
mined by dye tracer tests, is
greater than 0.6. (The modal
value is determined by di-
viding the time which corre-
sponds to the highest point of
the tracer residence time
distribution curve by the
theoretical detention time.) A
contact tank constructed with
baffles parallel to the longi-
tudinal axis of the chamber or a
long narrow channel having
a minimum length to width ratio
of 40:1 is recommended. Cross-
baffles in shallow chambers may
also be necessary to reduce
short circuiting caused by wind
currents.
L78
-------
15
9
c/>
bJ
CC
Ul
z
(T
3
o
o
10
I T
• 17.3 MIN CONTACT TIME, R=.933
•35.0 MIN CONTACT TIME, R=,933
-49.6 MIN CONTACT TIME, R=.932
0
5 10 15
APPLIED CHLORINE DOSE (mg/l)
(a) Filtered Effluent
20
o>
£
a
en
LJ
LJ
z
cc
o
10
0
17.3 MIN. CONTACT TIME, R=.847
• 35.0MIN.CONTACT TIME,R=.833
• 49.6MIN.CONTACT TIME,R = .82Z
Figure 6.
I
6 12 18 24 30
APPLIED CHLORINE DOSE (mg/l)
(b) Unfiltered Effluent
Chlorine dose vs. total residual — filtered
and unfiltered effluent.
0.0
-1.0
1 -2.0
o
o
0 -3.0
-4.0
-5.0
I7.S MIN. CONTACT TIME,R=.922
3S.OMIN.CONTACT TIME,R=.939
49.6MIN. CONTACT TIME,R=.9O8
T
O 12345
TOTAL CHLORINE RESIDUAL (mg/l)
(a) Filtered Effluent
o
e>
o
0.0
-1.0
-2.0
-3.0
-4.0
-5.0
I i
17.5 MIN. CONTACT TIME, R = .876
35.OMIN. CONTACT TIME, Rs.843
49.6MIN.CONTACT TIME, R= 823
0 2 4 6 8 10
TOTAL CHLORINE RESIDUAL (mg/l)
(b) Unfiltered Effluent
Figure 7, Coliform removal efficiencies--filtered
and unfiltered effluent.
-------
Solids removal. Baffles should
be provided for removal of
floating solids while provisions
should be made for draining the
contact tank and removing
settled solids. Duplicate
contact chambers should be
provided so that one can remain
in service while the other one
is being cleaned. Channel
widths should be wide enough to
allow easy access for cleaning.
Outfall lines. Outfall lines
may be used for chlorine contact
if they are flowing full at all
times, exhibit the proper
detention time, and preclude
infiltration and exfiltration.
Dechlorination
Dechlorination facilities may be
required in a case-by-case basis where
chlorinated effluent is being discharged
to biologically sensitive receiving
waters and/or to meet established chlo-
rine receiving water quality criteria.
Chlorine Supply
Sufficient storage should be pro-
vided to provide at least one spare
cylinder for each one in service. The
chlorination room should be maintained
at at least 55°F, but heat or direct
sunlight must never be applied directly
to the cylinders. The maximum withdrawal
rate for 100 and 150 pound cylinders
should be limited to 40 Ibs per day and,
for 2000 pound cylinders, to 400 Ibs per
day per cylinder. Scales and cylinder
handling equipment should be provided.
An automatic switch-over system should be
installed at facilities having less than
continuous operator attendance.
Piping and Valves
All piping and valves should be
approved by the Chlorine Institute.
Recommended piping is as follows:
1. Supply piping between cylinder
and chlorinator should be Sc.
80 black seamless steel pipe
with 2000 pound forged steel
fitting. Unions should be
ammonia type with lead gaskets.
2. Chlorine solution lines should
be Sc. 80 PVC, rubber-lined
steel, saran-lined steel, or
fiber cast pipe approved for
moist chlorine use. Valves
should be PVC, rubber-lined, or
PVC lined.
3. Injector line between chlori-
nator and injector should be So.
80 PVC or fiber cast approved
for moist chlorine use.
Chlorinators
Chlorinators should be sized so that
they are capable of providing a dose of
at least 10 mg/1 in the effluent. The
maximum feed rate required may vary from
pond to pond and should be determined on
an individual basis. Basically, there are
two types of chlorine gas Chlorinators.
1. Direct feed. This type of
chlorinator should be used only
in small facilities. Many
states will not approve use of
this type of chlorinator.
2. Vacuum feed. This type of
chlorinator has wide spread
application and is much safer to
use than direct feed.
Safety Equipment
The
should be
following
provided.
safety equ ipment
2.
3.
Exhaust fan located near floor
level and switched to come on
automatically when the chlori-
nation room is entered. The fan
should be of sufficient size to
produce one air change per
minute.
Emergency breathing apparatus
located near the door or outside
the chlorination room.
Emergency chlorine container
repair kits.
4. Chlorine leak detection.
5. In most cases, alarms should be
provided to alert the operator
in the event of deficiencies or
hazardous conditions.
Diffusers
Diffusers should be designed for a
minimum velocity through diffuser
holes of 10-12 feet per second and
installed such that they can be easily
removed for cleaning or replacement.
OPERATION AND MAINTENANCE
A properly designed chlorination
facility will only perform as well
as it is operated and maintained. Some
important aspects of operation and
maintenance are as follows:
180
-------
1. Cleaning of contact chambers.
Clean contact chambers reduce chlo-
rine demand and thus operational costs
significantly. Frequent cleaning is
especially important in chlorination of
pond effluents because - - - • •
puuu eiij.ueui.3 ueuause solids can
build up rapidly due to the settling of
algae and other aquatic organisms.
2. Sampling and analysis. The
amperometric method is probably the
most accurate method of testing for
chlorine residual. Frequent analysis
should be made for chlorine residual and
fecal coliform.
3. Chlorine dose. The chlorine
dose required to produce the desired
level of disinfection must be determined
on a case-by-case basis. Since the
amount of chlorine required varies
drastically with pond effluents, studies
should be conducted seasonally to identi-
fy changes in disinfection require-
ments. Dosage rates should be checked at
least daily. The chlorine residual
generally should be kept below 1 mg/1.
This, however, must be determined on
a case-by-case basis for each individual
pond system.
4. Records. Periodic, preferably
daily, records of chlorine dose, chlorine
residual, coliform counts, pH, chlorine
demand, etc., should be maintained.
5. Safety precautions. All opera-
tion and maintenance personnel should
be trained in safety precautions involv-
ing chlorine.
6. Miscellaneous precautions.
Operators must be alert to assure that
there is continually an adequate supply
of solution water, that chlorine in-
jectors do not become plugged with algae,
that strainers are frequently cleaned,
and generally that all mechanical equip-
ment is in good operation to assure the
highest possible chlorination efficiency.
EXAMPLES OF STABILIZATION
POND CHLORINATION
Variability in possible designs of
chlorination facilities for stabili-
zation ponds may best be pointed out by
citing several examples.
Rigby, Idaho
The Rigby treatment facility basi-
cally consists of a four cell system.
The first cell is aerated with two
mechanical aerators. The ponds treat
an average of about 0.25 mgd. Chlorina-
tion was added several years ago as
required by the discharge permit. The
chlorine contact chamber consists of
a well baffled rectangular concrete basin
as shown in Figure 8. The length/
width ratio well exceeds the recommended
design criteria of 40:1. A concrete scum
baffle removes flotables prior to dis-
charge. At peak flows, the detention
time is 1 hour.
Chlorine dose is usually set at the
amount of chlorine necessary to produce a
residual of 0.2 mg/1 at the end of the
contact period. Under these conditions,
chlorine dosage necessary to achieve the
0.2 mg/1 residual is around 5 mg/1.
Although a relatively low chlorine demand
and excellent disinfection are achieved
by this facility, there are several items
that could be improved upon. For one,
channels are too narrow for easy access
for solids removal and cleaning of the
contact basin. Fortunately, very
little solids are accumulated, even in
late summer when Daphnia blooms are a
problem.
Another difficulty lies with the use
of a direct feed chlorinator. On
several occasions, chlorine gas has been
detected being discharged directly
to the atmosphere, creating a po-tential
health hazard. Although a direct
feed chlorinator is simple to operate, it
does offer the serious disadvantage of
potentially creating health hazards,
particularly at facilities which are
infrequently inspected. Also, the city
has had some difficulty getting replace-
ment parts and has found it advantageous
to keep a good supply of spare parts in
stock.
Roosevelt, Utah
The Roosevelt facility is a new pond
system designed to treat 1.5 mgd.
The facility basically consists of a four
cell system. The last cell is a large
winter storage reservoir which also
serves as a final finishing pond.
Effluent is stored throughout the winter
and used to irrigate alfalfa in the
summer with center pivot, sprinkler
irrigation systems. Chlorination is
required prior to land application.
The chlorine contact chamber con-
sists of a 72" CMP. embedded in the
embankment of the winter storage pond.
This pressure conduit is designed
for a contact time of 1 hour at peak
pumping rates. Chlorination is ac-
complished by use of vacuum feed chlori-
nator fed by two 1-ton cylinders.
Chlorine is fed from both cylinders
simultaneously. Although this is not
necessary, it does avoid having to use
evaporators. The chlorinator feeds
181
-------
Figure 8. Rigby chlorine contact chamber.
at a rate sufficient for a dose of about
10 mg/1 chlorine. Because of the
newness of the facility, no major opera-
tional problems have been encountered
to date.
Mj.dvale, Utah
The Midvale facility is a 5 mgd
aerated lagoon system. Aeration is
accomplished by static tube diffused
aerators. When chlorination became
necessary, a nozzle type jet disinfection
system manufactured by Penberthy was
installed. In this type of system,
chlorine is rapidly mixed with the
effluent as it is forced through a jet
type nozzle. The importance of mixing
is emphasized in the system. The oper-
ator has found excellent disinfection
with substantial savings of chlorine. He
has estimated that the chlorine dose
required is more than 50 percent less
than it would have been with a conven-
tional disinfection system. Currently, a
chlorine dose of about 2 mg/1 is being
used to maintain a chlorine residual of
0.5-0.? mg/1. This dosage is consider-
ably less than the 6-7 mg/1 being re-
quired at an adjacent trickling filter
plant. The contact time necessary for
adequate disinfection has also been
reduced. At the Midvale plant, effluent
is discharged into an outfall ditch
following the jet disinfection and mixing
system. The ditch provides 30 minutes of
contact time for the effluent prior to
discharging it into the receiving water.
No major operational problems have been
encountered to date and the chlorine
demand has stabilized to a fairly con-
stant level. Occasionally, chlorine
demand will fluctuate in response to
industrial wastes which are periodically
discharged into the treatment facility.
No increase in chlorine demand has been
observed during times of high algae
concentration.
current discharge standards. With proper
design, careful monitoring, and con-
scientious operation and maintenance, it
is possible to efficiently achieve a
desired level of disinfection while
minimizing potential adverse effects.
However, it must be cautioned that while
many general design and operational
criteria are applicable, pond effluent
qualities are highly variable from
pond-to-pond and actual operational
control parameters must be established by
comprehensive field study for each
system.
REFERENCES
Brinkhead, C. E., and W. J. O'Brien.
'973. Lagoons and oxidation ponds.
JWPCF 45(10):1054-1059-
Collins, Harvey F., Robert E. Selleck,
and George C. White. 1971. Prob-
lems in obtaining adequate sewage
disinfection. Journal of the
Sanitary Engineering Division of
ASCE 97CSA5):549-562.
Dinges, Ray, and Alfred Rust. 1969.
Experimental chlorination of stabi-
lization pond effluent. Public
Works 100(3):98-101.
Echelberger, Wayne F., Joseph L. Pavoni,
Philip C. Singer, and Mark W.
Tenney. 1971. Disinfection of
algal laden waters. Journal
the Sanitary Engineering Division
ASCE 97(SA5):721-730.
EPA. 1977. Disinfection by chlorina-
tion. Design and operation and
maintenance guidelines as related to
t- Vi o PI no c n A ^ A m n j_ ,._i_j_._ _ i
of
of
the
program.
ton.
__ related to
PL 92-500 construction
Region X.
joui uuuxun grant
Seattle, Washing-
SUMMARY
Chlorination of pond effluents is
being required in many cases, to meet
Horn, Leonard W. 1972. Kinetics of
chlorine disinfection in an eco-
system. Journal of the Sanitary
Engineering Division of ASCE 98
(SA1):183-W.
182
-------
Kothandaraman, V., and R. L. Evans.
1972. Hydraulic model studies of
chlo rine contact tanks. JWPCF
44(4):625-663.
Kothandaraman, V., and R. L. Evans.
1974. Design and performance of
chlo .rine contact tanks.
Circular 119, Illinois State Water
Survey, Urbana, Illinois.
Kott, Yehuda. 1971. Chlorination
dynamics in wastewater effluents.
Journal of Sanitary Engineering
Division of ASCE 97(SA5):647-659.
Kott, Yehuda. 1973- Hazards associated
with the use of chlorinated oxida-
tion pond effluents for irrigation.
Water Research 7:853-862.
Marske, Donald M., and Jerry D. Boyle.
1973. Chlorine contact chamber
design - a field evaluation. Water
and Sewage Works 1 20(1):70-77 .
White, G. Clifford. 1973. Disinfection
practices in the San Francisco
Bay area. JWPCF 46(1 ) : 89-1 01.
Zaloum, R., and K. L. Murphy. 1974.
Reduction of oxygen demand of
treated wastewater by chlorination.
JWPCF 46(12):2770-2777.
Zillion, John A. 1972. Toxicity of
combined chlorine residuals to
fresh water fish. JWPCF 44(2):212-
220.
183
-------
COST ESTIMATES FOR OXIDATION POND SYSTEMS
Michael F. Torpy*
I. INTRODUCTION
Cost data have been compiled from
the literature, equipment manufac-
turers, and consultant engineers to
approximate the component costs of
small lagoon systems for various condi-
tions. The conditions considered were
usually evaluated for flowrates between
0.1 and 5.0 mgd and include changes
in lagoon retention time, land costs,
energy costs, and application rates
for land application units. The total
cost of each treatment unit of a lagoon
system was usually segmented by defining
capital, land, operation and mainte-
nance (O&M), and energy costs. The cost
data rely on some common assumptions
reflected in the reported costs. The
assumptions are:
1 .
prices.
All costs are based on 1978
2. Capital costs (which include
installation) are annualized with a
capital recovery factor based on an
interest rate of 5-5/8 percent compounded
for 20 years.
3.
value.
Capital equipment have no resale
4. Land resale value is identical
to purchase price and is evaluated
with a sinking fund factor at 5-5/8
percent interest for 20 years.
5. Labor
man-hour.
costs are $9.00 per
6. Crop revenues from land applica-
tion systems are calculated as net
profits at $40.00 per acre of land
irrigated.
"Michael F. Torpy is with EES
Division, Argonne National Lab., Argonne,
Illinois.
7. Pumping efficiencies vary from
61 percent in the lower flowrate ranges
to 65 percent in flowrates greater than
1.4 mgd.
Peak flow is two times average
flowrate.
II. COST OF LAGOON SYSTEM COMPONENTS
A. Pretreatment
Grit chamber and Bar Screens - The
capital costs for preliminary treat-
ment of small wastewater treatment plant
influents are described in Figure 1.
The operation and maintenance costs are
estimated by:
1. Labor at 1 man-hour per day.
2. Energy at 0.25 KWH per 1000
gallons (1).
B. Oxidation Ponds
1- Natural Aeration - The costs for
naturally aerated oxidation ponds
have been evaluated for variations in 1)
Storage season (or, conversely the
application season), and 2) land value.
Table 1 indicates the area required
for a range of average flowrates when the
storage season varies from 3 to 7 months
and assuming the maximum depth from the
pond surface is 8 feet and the roads
require an additional 15 percent of the
pond design area. Buffer zones and pond
lining were not considered. Tables 1 and
2 indicate the total land area and
volume, respectively, required for
naturally aerated lagoons with variations
in storage season.
Figures 2-4 describe the approximate
naturally aerated lagoon segment costs
with variations in the application
season. The application season refers to
the length of time during a year when the
lagoon effluents can be discharged and is
equal (in months) to 12-storage season
(in months).
184
-------
O
O
O
to
i-
co
o
o
z
o
h-
O
£E
CO
Z
O
o
,000
9
f
5
4
3
2
100
c
8
7
6
F
4
10
C
^^
^
/
S
/
/
/
/"
Z 3456789 2 3456789
).l 1.0
PEAK FLOWRATE (MGD)
Figure 1. Capital costs for preliminary treatments (2).
Table 1. Naturally aerated lagoon area
requirements.
Flow
(mgd)
Storage
3
Season (Months)
5
7
Area (Acres)
0.1
0.3
0.5
1.0
3.0
5.0
4
12
20
40
120
201
7
20
34
67
202
336
10
28
47
94
283
471
Table 2. Oxidation pond storage re-
quirements .
Flow
(mgd)
0.1
0.3
0.5
1.0
3.0
5.0
Storage
3
Storage
9.1
27.4
45.6
91.2
273.8
456.3
Season (Months)
5 7
Volume (106
15.2
45.6
76.0
152.1
456.3
760.4
gal)
21.3
63.8
106.4
212.8
638.4
1064.0
185
-------
Reservoir Construction
and Embankment Protection
100
O.I .2 .3 .4 .5 .6.7.8.91.0 2.0 3.0 4.05.0
FLOWRATE ( MGD)
Figure 2. Flowrate versus annual costs for oxidation
ponds.
100
.2 .3 .4 .5 -6.7.8.9I.O 2.0 3.0 4.05.0
FLOWRATE (MGD)
Figure 3. Flowrate versus annual cost for oxidation
ponds.
-------
D
0)
**
tn
o
o
o
z
Z
z
O.I .2 .3 ,4 .5 .6.7.8.91.0 2.0 3.0 4.05.0
FLOWRATE (MOD)
Figure *). Flowrate versus annual cost for oxidation
ponds.
3.0 4.0 5.0
FLOWRATE ( MGD)
Figure 5. Flowrate versus annual land costs for
submerged aeration ponds producing 85
percent BOD removal.
-------
10,000
9
a
7
6
5
CO
(-
CO
o
o
1,000
9
a
7
6
5
4
GO
OO
100
9
8
7
6
5
4
10
0.1
Figure 6.
|3,OOO/ACRE-
ISOO/ACRE
I t I I I I I I
.2 .3 .4 .5 .6.7.8.910 2.0
FLOWRATE ( MGD)
3.0 4.05.0
.2
.3 .4 .5 .6.7.8.91.0 2.0
FLOWRATE ( MGD)
3.0 4.05.0
Flowrate versus annual land costs for
submerged aeration ponds producing 90
percent BOD removal.
Figure 7.
Flowrate versus annual land costs for
submerged aeration ponds producing 95
percent BOD removal.
-------
2. Submerged Aeration - The ef-
ficiency of BOD removal for submerged
aeration in oxidation ponds varies with
the detention time. The costs for
submerged aeration were evaluated for 85,
90, and 95 percent BOD removal with the
assumptions that one person contributes
250 Ib of BOD per day and the pond depth
is 10 feet. Figures 5, 6, and 7 indicate
the land cost segment of the capital
costs at 85, 90, and 95 percent BOD
removal, respectively, when land costs
vary at $500.00, $1,000.00, and $3,000.00
per acre. Figure 8 includes other segment
costs for submerged aeration and apply
for BOD removal at 85, 90, and 95 percent
efficiency.
3. Surface Aeration - The costs of
surface aeration ponds operating at an 85
percent BOD removal efficiency were
calculated according to the design
specifications listed in Table 3. The
design and pump costs were provided by
Aqua-Aerobic Systems, Inc., Rockford, IL
(H). Other costs are updated costs from
Pound et al. (3). A summary of the costs
is described in Table 4.
C. Land Application Units
The use of land application units as
an alternative to discharging lagoon
effluents directly to a stream provides
some definite advantages. Some con-
siderations important to land application
choices are described in Table 5 and the
loading rates for alternative land
application units are described in Figure
9 according to soil types.
The annual energy costs for land
application units vary according to
the pumping requirements for the unit.
Figure 10 is provided to indicate
the annual energy costs for different
flowrate and total dynamic pumping
head requirements assuming energy costs
of $0.02/KWH and the application season
is 9 months. To calculate costs for
conditions that vary from a 9 month
application season, the respective
proportional values from Table 2 can be
used.
Figure 11 indicates the land re-
source requirements for land application
Table 3. Surface aeration lagoon design for 85 percent BOD removal.
Flow
(mgd)
0.1
1.0
5.0
# of
Lagoons
1
1
2
Depth
(ft)
10
14
14
1st Stage Lagoon
Surface,
Area (ftz)
4,096
28,900
71,300/ea
# of
Aerators
1
4
16
Aerator
Size (HP)
3.0
7.5
10.0
2nd Stage Lagoon
# of
Lagoons
1
I
4
Depth
(ft)
12
14
14
Surface3
Area (ft2)
8,056
70,300
98,100/ea
# of
Aerators
1
4
24
Aerator
Size (HP)
3.0
7.5
7.5
alncludes 1 day retention time for final settling.
Table 4. Costs of surface aeration oxidation ponds for 85 percent BOD removal.
Flow
(mgd)
0.1
1.0
5.0
Costs ($/year)
Capital
st°rage Pumps
Ponds r
2,059 422
7,642 2,266
27,769 12,750
O&M
475
1,016
3,143
Energy
1,568
15,677
88,840
Total
4,524
26,601
132,502
Population
Equivalent
Costs
($/per son/year)
9.05
5.32
5.30
189
-------
IOO.OOO
9
8
7
6
5
4
3
— IO.OOO
£ 9
S 8
>> 7
V. 6
** 5
"" 4
CO
I-
CO
O
O
1,000
9
8
7
6
5
4
3
100
Energy (ej)
1.04/KWH
0*M Costs
I I
I
O.I .2 .3 .4 .5 .6.7.8.91.0 2.0
FLOWRATE (MOD)
3.0 T4.0 5.0
UJ
5
o:
o
a
<
o
9
3
O
UJ
o
<
cc
LU
5
Figure 8. Flowrate versus annual costs for submerged
aeration ponds.
CLAY CLAY LOAM SILT LOAM LOAM SANDY LOAM LOAMY SAND SAND
SOIL TYPE
Figure 9- Soil type versus liquid loading rates for
different land application approaches
(5).
-------
ENERGY COST = $.02/KWH
APPLICATION SEASON = 9 MONTHS
100
•TOM = 25 ft
O
O
LU
CC.
O.I .2 .3 .4 .3 .6.7.8.91.0 2.0 3.0 4.05.0
FLOWRATE ( MGD)
Figure 10. Flowrate and TDH versus annual energy cost
for land application units.
Application Season = 5 months
@ 2 /week
Application Season = /months
(a) 2'Vweek
Application Season =9 months
@2"/«eek
Application Season = 9 months
(d> 4'Vweek
.3 .4 .5 .6.7.8.91.0 2.0
FLOWRATE (MGD)
3.0 4.0 5.0
Figure 11,
Flowrate and application rate versus land
requirements for land application treatment
units.
-------
Table 5. Comparison of irrigation, overland flow, and infiltration-percolation for
municipal wastewater (Pound et al., 1973) (9).
Type of Approach
Objective
Use as a treatment process with a
recovery of renovated water
Use for treatment beyond secondary:
1. For BOD and suspended solids
removal
2. For nitrogen removal
3. For phosphorus removal
Use to grow crops for sale
Use as direct recycle to the land
Use to recharge groundwater
Use in cold climates
Irrigation
Impractical
90 - 997,
Up to 90%a
80 - 99%
Excellent
Complete
0 - 30%
Fairb
Overland
Flow
50 to 60%
recovery
90 - 99%
70 - 90%
50 - 60%
Fair
Partial
0 - 10%
c
Infiltration-
percolation
Up to 90%
recovery
90 - 99%
0 - 80%
70 - 95%
Poor
Complete
Up to 90%
Excellent
aDependent upon crop uptake.
bConflicting data—woods irrigation acceptable, cropland irrigation marginal.
"Insufficient data.
units when the application season is
varied from 5-9 months and the appli-
cation rate is varied from 2 inches to 4
inches per week. The costs of four
land application units; solid set sprink-
ler, center pivot, overland flow,
and ridge and furrow, have been evaluated
according to an application season
of 9 months (storage season of 3 months),
a land value of $500.00 per acre and
energy costs of $0.02/KWH. Some of the
segment costs are updated from Pound
(3).
1. Solid Set Sprinkler - Figure 12
indicates the total annual costs for a
solid set sprinkler unit for varying
application seasons and rates with a
total dynamic pumping head of 100 feet
and energy cost -of $0.02/KWH. Figures 13
and 14 are provided to describe the
segment costs for capital, land, opera-
tion and maintenance, and energy can be
used with Figure 12 to calculate total
annual costs when conditions vary .from
those applied in Figure 12.
2. Center Pivot Spray Irrigation -
Figure 15 indicates the total annual
costs for center pivot spray irrigation
assuming a total dynamic pumping head
of 100 feet, land value of $500.00/acre
and an energy cost of $0.02/KWH. Figures
16 and 17 are supplements for Figure 15
to provide a basis for calculating total
annual costs under conditions that vary
from those of Figure 15.
3. Overland Flow - Figure 18 is
provided to estimate" the total annual
costs for overland flow with the assump-
tions that the total dynamic pumping
head is 50 feet, land value is
$500.00/acre and energy costs are
$0.02/KWH. Figures 19 and 20 can be
used to compliment Figure 18 under
varying assumptions.
*• Ridge and Furrow - Figures 21,
22, and 23 are provided for estimating
the total annual cost of ridge and furrow
irrigation under various resource cost
differences.
D. Polishing Units
1. R.££]i_!i£^i^_£ili®.r^ ~ Cost
estimates for rock media filters were
provided after a unit with a liquid
capacity of 0.6 x 10& gallons, designed
at 3-81 gallons per day of inflow per
ft3 of rock media (6). The capital
costs '(including pumps and installation)
are $66,000 and services a population
equivalent of 0.6 mgd with a detention
period of 24 hours and a large design
safety factor. Operation and maintenance
require 2 man hours per day with energy
pumping requirements of about 11,000 KWH
per year when operating continuously for
7 months. For BOD and suspended solids
influents of 160-300 ppm, the removal
efficiency is about 95 percent.
192
-------
Application Season = 5 months
Application Rate = 2"/week
Application Season = 7 months
Application Rote = 2"/week
Application Season =(9 months
Application Rote = 4'V week
TOTAL DYNAMIC HEAD = IOOFEET
LAND VALUE = 1500 /ACRE
ENERGY COST = $.O2/ACRE
1,000
APPLICATION SEASON = 9 MONTHS
APPLICATION RATE = 2"'/ WEEK
TOTAL DYNAMIC HEAD = 100 FEET
LAND VALUE = t 900/ACRE
ENERGY
COST
O.I .2 .3 .4 A .6.7.8.910 2.0
FLOWRATE (MOD)
3.O 4.05.0
Figure 12. Flowrate, application season, and applica-
tion rate versus total cost for a solid set
sprinkler unit.
100
O.I
.3 .4 .5 .6.7.891.0 2.0
FLOWRATE ( MOD)
3.0 4.05.0
Figure 13. Flowrate versus cost for a solid set
sprinkler unit.
-------
1,000
LAND VALUES
APPLICATION SEASON = 9 MONTHS
APPLICATION RATE = 2" / WEEK
TOTAL DYNAMIC HEAD = 100 FEET
ENERGY COST= t.OZ/KWH
O.I .2 .3 -4 .5 .6.7.8,91.0 2.0
FLOWRATE (MOD)
3.0 4.05.0
Application Season =5 months
Application Rate = 2"/»««h
Application Season = 7 months
Application Rote = 2 "/week 1
Application Season = 9 months
Application Rate = "
Application Season = 9 months
Application Rate = 4"/week
TOTAL DYNAMIC HEAD =100 FEET
LAND VALUE = 1500 /ACRE
ENERGY COST = J.02/KWH
Figure 14. Flowrate and land value versus total cost
for a solid set sprinkler unit.
1,000
Figure 15.
.2
.3 .4 .5 .6.7.8.91.0 2.0
FLOWRATE ( MGD)
3.0 4.0 5.0
Flowrate, application season, and applica-
tion rate versus total cost for a center
pivot unit.
-------
APPLICATION SEASON = 9 MONTHS
APPLICATION RATE = 2'V WEEK
TOTAL DYNAMIC HEAD = 100 FEET
LAND VALUE = I 500 ACRE
100
O.I .Z .3 .4 .5 .6.7.8.91.0 Z.O 3.0 4.05.0
FLOWRATE ( MGD)
APPLICATION SEASON = 9 MONTHS
APPLICATION RATE =2"/WEEK
TOTAL DYNAMIC HEAD = IOO FEET
ENERGY COST= t 02/KWH
1,000
.2 .3 .4 .5 .6.7.8.910 ZO 3.0 4.05.0
FLOWRATE (MGD)
Figure 16. Flowrate versus costs for a center pivot
unit.
Figure 17. Flowrate and land value versus total cost
for a center pivot unit.
-------
I.OOO
0.1
Figure 18.
Application Season = 5 month! -
Application Rate = 2" / month
Application
Season =7 months
Application
Rate = 2"f week
Application
Season = 9 months
Application
Rate = Z'Vweek
Application Season - 9 months
Application Rate = 4"/ week
TOTAL DYNAMIC HEAD = 50 FEET
LAND VALUE = tSOO/ACR£
ENERGY COST = f.02/KWH
J LJ
.2 .3 .4 .5 .6.7.8.91.0 2.0
FLOWRATE (MOD)
3.0 4.05.0
APPLICATION SEASON = 9 MONTHS
APPLICATION RATE = 2 / WEEK
TOTAL DYNAMIC. HEAD = 50 FEET
LAND VALUE = I 500/ACRE
100
.2
.3 .4 .5 .6.7.8.91.0 ZO
FLOWRATE { MGD)
3.0 4.0 5.0
Flowrate, application season, and applica-
tion rate versus total cost for overland
flow units.
Figure 19. Flowrate versus cost for overland flow
units.
-------
O.I
1,000000
e
7
6
5
APPLICATION SEASON = 9 MONTHS
APPLICATION RATE = 3"/WEEK
TOTAL DYNAMIC HEAD = 50 FEET
ENERGY COSTS = |.02/KWH
3 —
2 —
I I I I I
I III
.3 .4 .5 .6.7,8.91.0 Z.O
FLOWRATE ( MGD)
3.0 4.05.0
I.OOO
Figure 21.
Application Season =J5 months
Application Rate -1 /week —
Application Season = 7 months
Application Rat* - 2"/week ~
Application Season =9months
Application Rate = 2"/week
Application Season =9 months
Application Rate = 4' / week
TOTAL DYNAMIC HEAD = 60 FEET
LAND VALUE = (SOO/acre
ENERGY COST= 1.02/KWH
.2
.3 .4 .5 .6.7.8.91.0
2.0 3.0 4.0 5 O
Figure 20. Flowrate and land value versus total cost
for overland flow units.
FLOWRATE (MGD)
Flowrate, application season, and applica-
tion rate versus total cost for ridge and
furrow irrigation units.
-------
APPLICATION SEASON ^ 9 MONTHS
APPLICATION RATE = 2"/WEEK
TOTAL DYNAMIC HEAD = 5O FEET
ENERGY COST =|.O2/KWH
APPLICATION RATE = Z /WEEK
APPLICATION SEASON =9 MONTHS
TOTAL DYNAMIC HEAD = 50 FEET
LAND VALUE = f 50O/ACRE
100
.3 .4 .5 .6 .7.8.91.0 2.0
FLOWRATE (MOD)
Figure 22. Flowrate versus cost for ridge and furrow
irrigation units.
.2 .3 .4 .5 .6.7.8.91.0 2.0
FLOWRATE ( MGD)
3.0 4.O 5.0
Figure 23. Flowrate and land value versus total cost
for ridge and furrow irrigation units.
-------
2. Microscreens - The annual costs
for a 1.7 mgd tnicroscreen unit (7)
are listed below
Annual Cost
Capital - $595,000 $50,307
0&M , , 19,000
Energy (196 x 103 KWH/yr) 6 600
g $ . 033/KWH --- -
TOTAL $75,907
3 • I>iMM^ed_Aj. r_F lo t a t^o n - Th e
annual costs for a dissolved air flota-
tion unit with a 1.7 mgd capacity (7) are
listed below
Capital - $300,000 $25 365
O&M - $168,400 168,400
Energy (196 x 1 03 KWH/yr) 6,600
fi $ .033/KWH
TOTAL $200,365
4. Intermittent Sand Filters - The
costs for intermittent sand filters
are reported from the literature in 1973
dollars and listed below on the assump-
tion that the filters are cleaned manual-
ly (8).
Capital - $190,000
O&H (§ 2360 m-hour/yr)
E. Chlorination Unit
$16,065
18,880
The Chlorination costs for a range
of flowrates are described in Figure
24, assuming a chlorine dose of 5 mg/1
and a cost of $0.10/lb for chlorine
(3).
REFERENCES
1.
2.
3.
4.
Hagan, R. M., and E. B. Roberts.
1976. Energy Requirements for
Wastewater Treatment: Part 2.
Water and Sewage Works, Dec. p.
52-57.
Benjes, H.H., Jr. 1978. Small
Community Wastewater Treatment
Facilities-Biological Treatment
Systems. In Design Seminar Handout:
Small Wastewater Treatment Facili-
ties, EPA p. 98.
Pound, C. E., R. W. Crites, and D.
A. Griffes. 1975. Cost of Waste-
water Treatment by Land Application.
EPA (EPA-430/9-75-003).
Wight, J. 1978. Aqua-Aerobic
Systems, Inc., Rockford, Illinois.
Figure 24.
.3 .4 .6 .6.74.91,0 2.0
FLOWRATE (MGD)
3.0 4.05.0
Flowrate versus annual costs
for the Chlorination of la-
goon effluent.
5. Pound, C. E., and R. W. Crites.
1973. Wastewater Treatment and
Reuse by Land Application - Vol. II.
EPA (EPA-660/2-73-006b).
6. Walter, Ray V. 1968. Schaudt, Stem
and Walter, Inc., Eugene, Oregon.
7. Kormanik, R. A. 1978. Envirex,
Inc., Waukesha, Wisconsin.
8. Middlebrooks et al. 1978. Perfor-
mance and Upgrading of Wastewater
Stabilization Ponds. In Design
Seminar Handout: Small Wastewater
Treatment Facilities. USEPA.
199
-------
PERFORMANCE OF AERATED WASTEWATER STABILIZATION PONDS
E. J. Middlebrooks
J. H. Reynolds
C. H. Middlebrooks*
INTRODUCTION
Wastewater stabilization ponds are
effective in reducing BODg and have
only one basic disadvantage, i.e., high
concentrations of solids in the ef-
fluents. These solids leave the lagoon
along with the other constitutents and
can create problems in receiving streams.
Concentrations of suspended solids can
exceed 100 mg/1, but, as shown in the
detailed performance data presented
herein, such high concentrations are
usually limited to two to four months
during the year. However, during some
months of the year, the suspended solids
concentration exceeds the standard
specified by most regulatory agencies.
With the new standards proposed in the
September 2, 1976, issue of the Federal
Register, small flow systems will be
excluded from the suspended solids
effluent requirements provided that these
solids are in the form of algae. In
areas where water quality limited streams
occur, it is presumed that algae removal
will be required. Interpreting what
constitutes algae may create problems in
many locations, and it may require
extensive study to convince the regula-
tory agency that principally algae are
being discharged.
The Environmental Protection Agency
has produced excellent documents outlin-
ing the basic factors which need to be
corrected in order to ensure proper
design of wastewater stabilization ponds
(EPA, 1973b; EPA, 1974). These documents
may be obtained by writing to Technology
Transfer, U.S. Environmental Protection
Ag.ency. Further discussion of design of
wastewater stabilization ponds will be
omitted from this paper because of the
extensive amount of information available
through Technology Transfer and elsewhere.
*E. J. Middlebrooks is Dean, J. H.
Reynolds is Ass't Professor, College of
Engineering, and C. H. Middlebrooks is
Computer Scientist, College of Science,
Utah State University, Logan, Utah.
To satisfy the need for reliable
lagoon performance data, in 1974 the U.S.
Environmental Protection Agency sponsored
four intensive facultative lagoon perfor-
mance studies and five intensive aerated
lagoon performance studies. The four
facultative lagoon performance studies
were described in the paper by Finney
and Middlebrooks presented in these
proceedings. The aerated lagoons were
located at Bixby, Oklahoma (Reid, 1977),
Pawnee, Illinois (Gurnham & Assoicates,
Inc., 1976), GulfPort, Mississippi
(Englande, 1975), Lake Koshkonong,
Wisconsin (Polkowski, 1977), and Windber,
Pennsylvania. Data collection encom-
passed 12 months with four separate 30
consecutive day sampling periods once
each season.
Aerated waste stabilization ponds
are medium depth, man-made basins de-
signed for the biological treatment of
wastewater. A mechanical aeration device
is used to supply supplemental oxygen to
the system. In general, an aerated lagoon
is aerobic throughout its entire depth.
The mechanical aeration device may cause
turbulent mixing (i.e., surface aerator)
or may produce laminar flow conditions
(diffused air systems).
Although the development, history,
and design of aerated wastewater stabi-
lization ponds have been reported by
several investigators (Boulier and
Atchinson, 1974; Bartsch and Randall,
1971; McKinney, 1970) very little reli-
able year-round performance data was
available until the U.S. Environmental
Protection Agency funded the evaluation
of five aerated lagoon systems (Lewis,
1977). A portion of the data from these
studies will be presented in the fol-
lowing paragraphs.
SITE DESCRIPTION
Bixby, Oklahoma
A diagram of the Bixby, Oklahoma,
aerated lagoon system is shown in Figure
1 (Reid, 1977). The system consists of
200
-------
PUMP I
SCREEN
LIFT STATION
FM
-CXI
PUMP 2
LEGEND
I
E
R
A
D
EP
E1
E*
e°
INFLUENT
EFFLUENT
RETURN EFF.
AIR
DRAIN
PLANT EFF.
LAGOON 1 EFF.
LAGOON 2 EFF.
OVERFLOW 8 E
LAGOON I
BLOWER
HOUSE
LAGOON 2
TO RIVER
Figure 1. Aerated lagoon system at Bixby, Oklahoma (Reid, 1977).
two aerated cells with a total surface
area of 2.3 ha (5.8 acres). It was
designed to treat 336 kg BODc/day (740
Ibs BOD5/day) with a hydraulic loading
rate of 1551 m3/day (0.4 mgd). There
is no chlorination facility at the site.
The hydraulic retention time is 67.5
days.
Pawnee, Illinois
A diagram of the Pawnee, Illinois,
aerated lagoon system is shown in Figure
2 (Gurnham and Associates, Inc., 1976).
The system consists of three aerated
cells in series with a total surface area
of 1.145 ha (11.0 acres). The design
flowrate was 1893 m3/day (0.5 mgd) with
an organic load of 386 kg BOD5/day (850
Ibs BOD5/day) and a theoretical hydraulic
retention time of 60.1 days. The facil-
ity is equipped with chlorination disin-
fection and a slow sand filter for
polishing the effluent. Data reported
below were collected prior to the filters
and represent only lagoon performance.
Gulfport, Mississippi
A diagram of the Gulfport, Missis-
sippi, aerated lagoon system is shown
in Figure 3 (Englande, 1975). The system
consists of two aerated lagoons in series
with a total surface area of 2.5 ha (6.3
acres). The system was designed to treat
1893 m3/day (0.5 mgd) with a total
theoretical hydraulic retention time of
26.2 days. The organic load on the first
cell in the series was 374 kg BOD^/
CELL I
CELL Z
A
Baffle
CELL 3
SCALE: i"= 120' (Approx.)
Manhole
2 Wei Well
3 Compressor House
4 Chlorine Contact Tank
Figure 2. Aerated lagoon system at
Pawnee, Illinois (Gurnham
and Associates, Inc., 1976).
201
-------
CELL NO.
A 1
A2
S2
S3
SURF. DIM.
206' xS35'
407' « 412'
95' x 205'
65' « 270'
OEPD-
6.3 '
6.3'
6'
6'
FLAT BRANCH
i „FINAL EFFLUENT
,CELL S4
e" F. M.>
15" 01 A.-
\ /
\ X
X
CELL X2
/ ^^
/ \
/ X
V /
\ /
\l
CELL XI
/\
1 CL2 COM{
i
&
i
CELL
§1
"«™"»"™"
k
CELL
S2
^
>
1
CELL
SI -
f
CELL Al
D (5)
yf\ FLOW MONITORING STATION
£\ SAMPLE MONITORING STATION
© AERATOR (HP)
i WEIR BOX
O MANHOLE
CELL A2
SCALE: i =100
Figure 3- Aerated lagoon system at Gulfport, Mississippi (Englande,1975).
day/ha (331 Ibs BOD5/day/acre) and 86
kg BOD5/day/ha (77 Ibs BOD5/day/aore)
on the second cell in the series. The
system is equipped with a ohlorination
facility.
Lake Koshkonong, Wisconsin
A diagram of the Lake Koshkonong,
Wisconsin, aerated lagoon system is shown
in Figure 4 (Polkowski, 1977). The
system consists of three aerated cells
with a total surface area of 2.8 ha (6.9
acres) followed by chlorination. The
design flow was 2271 nH/day (0.6 mgd)
with a design organic load of 467 kg
BOD5/day (1,028 Ibs BOD5/day). The
current organic loading rate is 248 kg
BODr/day (545 Ibs BOD5/day) with a theo-
retical hydraulic retention time of 57
days.
Windber, Pennsylvannia
The Windber, Pennsylvania, aerated
lagoon system consists of three cells
with a total surface area of 8.4 ha (20.7
acres) followed by chlorination. The
design flow rate was 7,576 tin/day (2.0
mgd) with a design organic loading rate
_ DRAINAGE DITCH
'TO ROCK RIVER
PONO NO. I
BY-PASS
COMMINUTOR AND
PUMPING STATION
PONO NO. 3
BY- PASS
1370 U.F.-I2" OUTFALL
CMLORINATORS
Ti -3000 L.F.-I2"
? — ;
FORCE MAIN
Figure 4. Aerated lagoon system at Lake
Koshkonong, Wisconsin (Polkow-
ski, 1977).
202
-------
of approximately 1,369 kg BOD5/day (3,000
Ibs BOD5/day). The design mean hydraulic
residence time was 30 days for the 3
cells operating in series. Actual
influent flow rates varied from 3,000 to
5,300 m^/day (0.8 to 1 . J| mgd), the
actual organic loading rate was approxi-
mately 924 kg BOD5/day (2,030 Ibs
BOD5/day), and the theoretical mean
hydraulic residence time was approxi-
mately 55 days.
PERFORMANCE
Biochemical Oxygen Demand (6005')
The monthly average effluent bio-
chemical oxygen demand (BODr) removal
for the five previously described aerated
lagoon systems is reported in Table 1.
The monthly average effluent BODc
concentrations are c'ompared with the
Table 1. Performance summary of aerated lagoons.
(No.
Date Description
Sampling Days)
Biochemical
Oxygen Demand
(mg/1)
Suspended Solids
(mg/1)
Geometric Mean
Fecal Coliform
(No/ 100 ml)
Influent Effluent Influent Effluent Influent Effluent
PAWNEE, ILLINOIS
March, 1976 (7)
April (30)
May (7)
June (7)
July (31)
Axigus t ( 7 )
September (7)
October (31)
November (7)
December (7)
January (0)
February (7)
March (30)
Average
Q= 1893 m3/day
Surface area
= 4.45 ha
3 cell system
Chlorination
provided
Slow Sand Filter
provided.
Performance
data represent
only lagoon
performance .
233
277
470
470
452
602
578
799
548
554
-
395
296
473
3
3
3
6
3
2
2
2
2
3
-
4
10
4
178
236
544
370
768
758
529
678
560
543
-
387
417
497
22
10
23
52
7
8
21
25
14
24
_
19
29
21
_
8
50
70
235
210
3
44
5
6
-
2
<1
15
GULFPORT, MISSISSIPPI
December, 1975 (7) Q = 1893 tn3/day
January, 1976 (30) Surface area
2.5 ha
2 cell system
Chlorination
provided
February (7)
March (7)
April (30)
May (7)
June (7)
July (30)
August (7)
September (30)
October (7)
November (7)
Average
WINDBER, PENNSYLVANIA
November, 1975 (7) Q=3407 mj/day
December (7) 3 cell system
January (7)
February (29)
March (8)
April (7)
May (29)
June (7)
July (27)
August (11)
September (7)
October (30)
Average
BIXBY, OKLAHOMA ,
January, 1976 (24) Q=1552 mj/day
February (7) Surface area
March (7) = 2,3 ha
April (25) 2 cell system
178
214
199
192
178
175
171
134
151
170
171
186
177
177
203
152
220
186
155
201
182
145
162
173
106
172
368
504
460
402
24
26
20
25
26
21
23
20
25
30
34
27
25
1
5
9
10
9
5
10
17
26
16
4
17
11
48
41
53
36
223
291
194
195
172
145
272
191
122
146
117
172
187
186
178
121
107
124
128
167
158
149
182
177
151
152
323
199
236
314
42
32
47
43
34
38
38
33
30
19
16
36
34
2
4
13
10
15
6
13
16
10
10
7
4
9
51
46
85
63
509
169
124
1,222
2,708
2,456
2,687
1,193
10,782
16,259
21,638
58,745
4,802
2
2
3
2
6
2
2
2
2
2
3
3
3
11,042 4,669
203
-------
Table 1, Continued.
Date
Biochemical
Oxygen Demand
Description (mg/1)
Suspended Solids
(mg/1)
Geometric Mean
Fecal Coliform
(No/ 100 ml)
Influent Effluent Influent Effluent Influent Effluent
May (9)
June (7)
July (21)
August (9)
September (3)
October (6)
November (19)
Average
No chlorination
provided
448
-
355
212
330
388
383
388
36
-
20
14
40
19
24
32
250
230
254
282
213
230
289
256
57
96
71
38
28
51
36
5.6
-
-
-
-
-
-
-
-
LAKE KOSHKONONG. WISCONSIN .
December, 1975
January, 1976
February (7)
March (7)
April (30)
May (7)
June (7)
July (30)
August (7)
September (7)
October (30)
November (7)
Average
(7) Q= 2271 mj/day
(30) Surface area
= 2.3 ha
3 cell lagoon
system
Chlorination
provided
89
96
73
37
55
71
86
93
118
113
102
87
85
8
10
5
11
10
13
11
20
19
17
11
4
12
184
115
123
48
64
64
100
133
183
126
114
116
110
4
3
2
26
22
55
19
23
16
21
8
5
17
-
-
-
-
-
-
-
-
-
-
-
-
-
Federal Secondary Treatment
of 30 mg/1 in Figure 5.
Standard system, were capable of producing a
In general, all of the systems
studies, except the Bixby, Oklahoma,
final effluent BOD5 concentration
of 30 mg/1. Average monthly effluent
BODcj concentrations appear to be in-
dependent of influent BODg concentra-
100
O FWVNEE, ILLINOIS (WITHOUT FILTRATION)
---•O---- GULFPQRT, MISSISSIPPI
—£* BIXBY, OKLAHOMA
D WIND6ER, PENNSYLVANIA
- 47- - LAKE KOSHKONONG, WISCONSIN
v-
A
' \ Q FEDERAL
/ ,V \ DISCHARGE STANDARD
3 N
D
1975
F
1976
M A
1 T
M J
1
J
I
A
l
S
0
i
N
!
D
1976
1 i
F M
197 r
Figure 5. Aerated lagoon Biochemical Oxygen Demand (6005) removal performance.
204
-------
tion fluctuations and are also not
significantly affected by seasonal
variations in temperature.
Average monthly influent BODg
concentrations at Bixby, Oklahoma,
ranged from 212 mg/1 to 504 tng/1 with
an average of 388 mg/1 during the study
period reported. The design influent
BODg concentration was 240 mg/1, or only
62 percent of the actual influent con-
centration. The mean flow rate during
the period of study was 523 m3 day (0.123
mgd) which is less than one third of
the design flow rate. The Bixby sy-
stem was designed to treat 336 kg BODc/
day (740 Ibs BODc/day), and apparently
a load of only 203 kg BOD5/day (446 Ibs
BOD5/day) was entering the lagoon. The
only major difference between the Bixby
and other aerated lagoons is the number
of cells. Bixby has only 2 cells in
series. Based upon the results of
studies with facultative lagoons which
show improved performance with an in-
crease in cell number, this difference in
configuration could account for the
relatively poor performance by the Bixby
system. However, there are many other
possible explanations, i.e., operating
procedures, inadequate air supply, short
circuiting (related to number of cells in
series), etc.
The results of these studies in-
dicate that aerated lagoons which are
properly designed, operated, and main-
tained can consistently produce an
effluent BOD concentration of less
than 30 mg/1. In addition, effluent
quality is not seriously affected by
seasonal climate variations.
SuspendedSolids Removal
Performance ~~ ~ ~~
The monthly average suspended
solids removal performance of the five
previously described aerated lagoon
systems is reported in Table 1. The
monthly average effluent suspended solids
concentrations for each system is
illustrated in Figure 6. At present
there is no specific Federal Secondary
Treatment Standard for effluent suspended
solids concentrations in aerated lagoon
effluents.
In general, the effluent suspended
solids concentration from three of
the aerated lagoon systems tend to
increase significantly during the warm
summer months. However, two of the
aerated lagoon systems (Windber, Penn-
sylvania and Gulfport, Mississippi)
produce a relatively constant effluent
suspended solids concentration throughout
the entire year.
Average monthly effluent suspended
solids concentrations ranged from 2 mg/1
at Windber, Pennsylvania, in November,
1975, to 96 mg/1 at Bixby, Oklahoma, in
—O— MWNEE, ILLINOIS (WITHOUT FILTRATION)
---O— GULFPORT, MlSSISSffl
—£>r- 8IXBY, OKLAHOMA
--O- WIND6ER, PENNSYLVANIA
LAKE KOSHKONONG, WISCONSIN
, FEDERAL
P DISCHARGE STANDARD
0
^_
N
D
1975
1976
— i — r~
M A
_1 , ,
M J
TTT
O
N
0
1976
F
1977
M
Figure
6. Aerated lagoon suspended solids removal performance.
205
-------
June, 1976. The average monthly effluent
suspended solids concentration for
the Windber, Pennsylvania site never
exceeded 30 mg/1 throughout the entire
study period. In addition, the average
monthly effluent suspended solid con-
centrations of the Pawnee, Illinois,
and the Lake Koshkonong, Wisconsin
sites only exceeded 30 mg/1 during one
of the months reported.
The results of these studies indi-
cate that aerated lagoon effluent sus-
pended solids concentrations are vari-
able. However, a well designed, oper-
ated, and maintained aerated lagoon
can produce final effluents with a low
suspended solids concentrations.
Fecal Coliform Removal
Performance
The monthly geometric mean fecal
coliform removal performance of three of
the five previous described aerated
lagoon systems is reported in Table 1.
Fecal coliform data were not available
for the Lake Koshkonong, Wisconsin, site
and only one monthly geometric mean fecal
coliform value was available for Bixby,
Oklahoma. The monthly geometric mean
effluent fecal coliform concentration
compared to a concentration of 200
organisms/100 ml is illustrated in Figure
All of the aerated lagoon systems,
except the Bixby, Oklahoma, sites have
chlorination disinfection. Therefore,
the data actually indicate the suscept-
ibility of aerated lagoon effluent to
chlorination. In general, the Windber,
Pennsylvania, and the Pawnee, Illinois,
systems produced final effluent monthly
geometric mean fecal coliform concentra-
tions of less than 200 organisms/100 ml.
The non-chlorinated Bixby, Oklahoma site
singe data point indicates a high ef-
fluent fecal coliform concentration. The
Gulfport, Mississippi system produced an
effluent containing more than 200 fecal
coliform/100 ml most of the time, but the
fecal coliforms were measured in effluent
samples from a holding pond with a long
detention time following the addition of
the chlorine. Therefore, aftergrowth of
the fecal coliform probably accounted for
the high concentrations.
SUMMARY
From the limited aerated lagoon
performance data currently available,
it appears that (a) aerated lagoons
can produce an effluent BODj- concen-
K)4
(0s
O PWVNEE, ILLINOIS (WITHOUT FILTRATION)
—-O— - GULFPORT, MISSISSIPPI J3- — 'Q"
_._O_._ \MNDBER, PENNSYLVANIA P"'
—-o
O O-*"
F
3 N
F
D
1975
1
F
1976
I 1
M A
I 1
M J
1
J
1 I
A S
I
0
!
N
I
D
1976
1
F
1977
I
M
Figure 7. Aerated lagoon fecal coliform removal performance.
206
-------
tration of less than 30.0 mg/1, (b)
aerated lagoon suspended solids concen-
trations are affected by seasonal varia-
tions, and (c) aerated lagoon effluent
can be satisfactorily disinfected with
chlorination.
REFERENCES
Bartsch, E.H. and C.W. Randall. 1971.
Aerated Lagoons—A report on the
State of the Art. Jour. Water
Poll. Control Fed., April.
Boulier, G.A. and T.J. Atchison. 1971*.
Aerated Facultative Lagoon Process.
Hinde Engineering Company. Highland
Park, Illinois.
Englande, A.J. 1975. Performance
Evaluation of Lagoon System at North
Gulfport, Mississippi. Quarterly
Report. EPA Grant No. R803899-01.
Tulane University. Belle Chasse,
La.
Environmental Protection Agency. 1973.
Upgrading Lagoons. Technology
Transfer, Washington, D.C., August.
Environmental Protection Agency. 197**.
Process Design Manual for Upgrading
Existing Wastewater Treatment
Plants. Technology Transfer, Wash-
ington, D.C., October, 1971.
Gurnham and Associates, Inc. 1976.
Personal Communication to Roger
Alexander from W.T. Fetherston.
Chicago, Illinois.
Lewis, R.F. 1977. Personal Communica-
tion. Environmental Protection
Agency, Cincinnati, Ohio.
McKinney, R.E. 1970. Second Interna-
tional Sympoisum for Waste Treatment
Lagoons, June 23-25, 1970, Kansas,
Missouri.
Polkowski, L.B. 1977. Personal Com-
munication. University of Wisconsin,
Madison, Wisconsin.
Reid, G.W.
t i o n .
Norman
1977. Personal Communica-
University of Oklahoma,
Oklahoma.
207
-------
AUTHOR INDEX
Abd-El-Bary
Adriano. D. C.
Aguirre, J.
Ahlstrom, S. B.
Allen, G. H.
Allen, M. B.
Alsten, C.
Amin, P.M.
Anderson, D. R.
Andrew, J.
Armstrong, D. L.
Aschner, M.
Atchison, T.J.
Atherton, J. J .
Aziz, K. M. S.
B
Bagnall, L. 0.
Bain, R. C., Jr.
Baker, D. C.
Barber, B. P.
Bardach, J. E.
Bare, W. F.
Barker, L. Sheldon
Barnes, T. C.
Barsotn, George
Bartley, C. H.
Bartsch, E.H.
Baxter, S. S.
Beauchamp, H. E.
Bella, D. A.
Benemann, J. R.
Benjes, H. H. , Jr.
Berg, E. J. M.
Bernarde, M. A.
Bernstein, L.
Berthouex, P. M.
Biggs, D. F.
Bishop, A. B.
Bishop, R. P.
Boleyn, B. J.
Bonde, G. J.
Borrelli, J.
Boulier, G.A.
Bouwer, H.
Boyle, J. D.
Brinkhead, C. E.
Brown and Caldwell,
Const. Eng.
Bunch, Robert L.
Burman, R. D.
Caldwell, D. H.
Camp, T. R.
Canter, L. W.
Carraichael, W. W.
101, 123,
140, 144
171
45, 49
51
143, 144
90, 91
124
12
171, 172
8, 13
170, 171, 172
13
200, 207
12
10, 14
128, 144
6, 12
144
101, 103
124, 144
47, 49
63
134, 144
2, 6, 12
12
200, 207
171
12
86, 88, 89
126, 127, 144
199
167, 171
170, 171
10, 14
86
14
35
146, 157, 165
88, 89
12
171, 172
200, 207
167, 171
175, 183
173. 182
73
2, 6, 12
171, 172
73, 92, 103, 122
122
24, 35
10, 14
Carnes, R. A.
Carpenter, L. R.
Carpenter, R. L.
Carroll, B. J.
CH2M HILL
Chaiken, E. I.
Chisholm, K.
Chorin-Kirsch, I.
Christie, A. E.
Clark, H. F.
Cleave, M. L.
Coetzee, 0. J.
Cohn, M. M.
Coleman, M. S.
Collier, R. E.
Collins, H. F.
Conely, J. E.
Cooper, R. C.
Cornell, D. A.
Cravens, J. B.
Crites, R. W.
Culley, D. D., Jr.
Davis, E. M.
Del Fosse, E. S.
Demirjian, Y. A.
Dillenberg, H. 0.
Dinges, R.
173, 174, 182
Dinsdale, M. T.
Drews, R. J. L. C.
Dryden, F. D.
Duffer, W. R.
10, 14
8, 12
144
7, 12
73, 74
74
92, 103
13
12
12
88, 90, 91
7, 12
171
12
12
175, 182
12
8, 13
127, 144
92, 93, 103
199
126, 127, 129, 144
37, 49
129, 135, 140, 144
168, 171
10, 14
47, 49, 129, 144,
88, 89
7, 12
73
125, 126, 144
Echelberger, W. F.
Ehreth, D. J.
Emery, R. M.
Emrich, G. H.
Engineering-Science Inc.
Englande, A.J.
Eppley, R. W.
173, 174, 182
14
8, 13
170, 171
37, 49
24, 35, 200, 201,
86, 88, 89, 90
EPA 18, 19, 20, 21, 24, 34, 35,
38, 39, 49, 50, 124, 126, 144, 169,
171, 182, 200, 207
Espino, E. 49
Evans, R. L. 175, 183
Eways, M. J. 140, 144
Fair, G. M.
Falkenborg, D. H.
Fay, P.
Filip, D. S.
Finney, Brad A.
Fjerdingstad, E.
149, 165
14, 144
89, 91
165
18
12
208
-------
Fogg, G. E.
Ford, D. L.
Fourie, N. A.
Fox, J. L.
Friedman, A. A.
Fuller, S. L. H.
Ganapati, S. V.
Gann, J. D.
Garland, T. R.
Gearheart, R. A.
Geiser, E. S.
Geldreich, E. E.
Gentry, R. E.
Gerba, C. P.
Geyer, J. C.
Gloyna, E. F.
46, 48, 49,
Golueke, C. G.
Gorden, J.
Gorham, P. R.
Gotaas, H. B.
Green, D. P.
Greene, J. C.
Grenney, W. J.
Griffes, D. A.
Griffith, J. S.
Gurnham and Associates
H
Hagan, R. M.
Hanisak, M. D.
Harris, S. E. 146,
Hart, B. A.
Hart, C. W., Jr.
Harvey, R. M.
Hassall, K. A.
Hayami, H.
Henly, D. E.
Hermann, E. R.
Herring, M.
Hiatt, A. L.
Hicken, B. T.
Hill, D. 0.
Hill, D. W. 146,
Hillman, W. S.
Hirsekorn, R. A.
Holmes, R. W.
Horn, L. M.
Horn, L. W.
Horn, L. W.
Huang, J.
Huff, C. B.
Ichirnura, S.
Jenkins, D.
Johnson, B. A.
Jokela, A. T.
Jokela, A. W.
Jones, W. B.
Joshi, S. R.
Kereiakes, J.
Keveren, R. I.
Kiefer, D. A.
88, 89, 90, 91
48, 49
12
126, 144
73
138, 144
7, 12
7, 12
13
86
73
7, 12
7, 12
171
165
29, 30 36, 37, 45,
2, 125, 144
47, 49, 103, 122, 123
145
9, 14
47, 49, 122
6
9, 13
35, 86
199
73
tes 200, 201, 207
199
145
147, 148, 149, 157, 165
13
138, 144
126, 144
9, 13
10, 14
13
122
48, 49
73, 122
167, 171
6, 12
153, 154, 155, 156, 165
126, 127, 129, 144
86
89
47 , 49
173, 182
8 13
v j -«--J
40
"T J
12
38, 49
J v J ' •*
9, 13
J ) — '
17Q
J. | _}
73
73
47, 49
8, 12
13
135, 144
88, 89
Kilham, P.
King, D. L.
Klopfer, D. C.
Koopman, B. L.
Kormanik, R. A.
Kothandaraman, V.
Kott, Y.
L
Larsen, T. B.
Laventer, C.
Lawrence, C. H.
Lecuyer, R. P.
Levelille, G. A.
Levenspiel, 0.
Lewis, R.W. 4
Little, J. A.
Loehr, R. C.
Lovell, R. T.
Lyerly, R. L.
M
Malchow-Moller, 0.
Malhotra, S. K.
Malina, J. F. , Jr.
Malone, H. K.
Maloney, T. E.
Marais, G. v. R, 8,
Marshall, G. R.
Marshall, R. T.
Marske, D. M.
Marten, J. H.
Martin, D. M.
Martin, J. L.
•Mashini, C. I.
Mayo, Francis T.
McCarty, P. L.
McDonald, R. C.
McDowell, M. E.
McGarry, M. C.
McKim, H.
McKinney, R.E. 12,
200, 207
McLarney, W. 0.
Medsker, L. L.
Mees, Q. M.
Meiring, P. G. J.
Melmed, L. N.
Melnick, J. L.
Merwin, E.
Messinger, S. S.
Metcalf, T. G.
Metcalf and Eddy Inc.
Middlebrooks, C.H.
Middlebrooks, E. J.
73, 86, 126, 144,
Middleton, F. M.
Miller, W. E.
Mitchum, A. L.
Morimoto, K.
Morris, M. E.
Moyer, J. E.
Murphy, K. L.
Myers, E. A.
Myers, R. B.
N
Narayan, L. V.
Nestnan, R.
Nevels, E. M.
00 on
OO , V J
6, 12
v t •*•*-
13
104, 122, 144
92, 93, 103, 199
175, 183
173, 174, 183
26, 28, 36'
13
12
127, 128, 144
14
34, 36
, 14, 144, 200, 207
7, 12
' t •*• *~
14
9. 13
J 1 j. _j
144
7, 12
167, 171
37, 49
12
10, 14
12, 30, 31, 33, 36
73, 86, 146, 165
12
175, 183
127, 144
86
86
13
1
12
145
10, 14
25, 27, 36, 73
13
86, 125, 126, 144.
124, 144
9, 13
73
45, 49
8, 13
171
13
146, 157, 165
12
127, 144
200
14, 18, 47, 48, 49,
146, 165, 199, 200
6, 12
9, 13
12
14
13
124, 125, 144
173, 183
167, 171
127, 128, 144
9, 13
7, 12
14
209
-------
NOAA (National Oceanic and
Atmospheric Administration)
Nunez, W. J. Ill
o
O'Brien, W. J. 75,
Okano , T .
O'Kelly, J. C.
Okun, D. A.
Orton, R. F.
36
9, 13
86, 173, 182
14
8, 13
7, 12, 165
171, 172
Oswald, W. J. 38, 47, 49, 103, 104, 122,
123, 125, 126, 144
P
Palazzo, A.
Palmer, C. M.
Parhad, N. H.
Parker, C. D.
Parker, D. S. 47, 49
Pavoni, J. L.
Peoples, R. F.
Pescod, M. B.
Phelps, E. B.
Pierce, W. H.
Polkowski, L.B.
Poloncsik, S.
Porcella, D. B.
Pound, C. E.
Powell, R. C.
R
iamani, R.
Randall, C.W.
Rao, N. V.
Raymond, Vail and Associates
Reed, S. C.
Reid, G.W.
Reynolds, E. C.
13
9, 13
8, 12
47, 49, 73
, 73, 92, 103
182
93, 103
25, 27, 36
171
12
200, 202, 207
74
86
189, 199
14
8, 13, 122
200, 207
8, 12
122
13
200, 207
51
Reynolds, J. H. 74, 86, 122, 146, 147,
149, 165
Rhett, John T.
Roberts, E. B.
Robertson, J. A.
Rosen, A. A.
Roy, A. D.
Roy, A. F.
Rupke, J. W. G.
Russell, Jerry
Rust, A.
Ruttner, F.
Ryckman, D. W.
Ryther, J. H.
S
Safferman, R. S.
Scaife, B. D.
Scakey, L. A.
Scarpino, P.
Schwimmer, D.
Schwimmer, M.
Sellars, J. N.
Selleck, R. E.
Serfling, S. A.
Shino, K.
Shiroyama, T.
Shindala, A.
Silvey, J. K.
72
199
12
13
12
12
92, 103
146
173, 174, 182
144
6, 12
124, 128, 145
9, 10, 13, 14
13
9, 13
13
9, 10, 14
9, 10, 14
14
175, 182
124, 130, 145
10, 14
13
6, 12
9, 13
Singer, P. C.
Slanetz, L. W.
Smallhorst, E. E.
Smayda, T. J.
Sletten, R.
Smith, Stanley M.
Sobsey, M. D.
Stander, G. J.
Steel, W.
Stern, G.
Stewart, M. J.
Stewart, W. D. P.
Strickland, J. D. H.
Stutz-McDonald, S. E.
Sullivan, R. H.
Svore, J.
Swanson, Gregory R.
T
Tenney, M. W.
Thirumurthi, Dhandapani
Thomas, J. F.
Tischler, L. F.
Titman, D.
Tolmsoff, A. J.
Torpy, M. F.
Tsuchida, M.
Tucker, D. L.
Tupyi, B.
Turvey, M. D.
U
Uhte, W. R.
V
Van-Heuvelen, W.
Villacorte, G. V.
Visher, S. S.
W
Wallace, A. T. 74
Wallis, C.
Walsby, A. E.
Walter, R. V.
Weimer, R. C.
Weller, R.
Weissman, J. C.
White, G. C. 173
Wight, J.
Williams, J.
Williams, L. D.
Williamson, K. J. 75,
Wilson, C. D.
Witt, N. F.
Wixson, B. G.
Wolverton, B. C. 126,
140, 145
WPCF
Wyatt, T. T.
Y
Yamamato, S.
Yu, K. Y.
Z
Zaloum, R.
Zillich, J. A.
Zolteck, J.
182
7, 12
<^
88, 89
13
15
8, 13
45, 49
167, 171
73
73
89, 91
86, 89
86, 90, 91
171
5
75, 88, 89, 90
182
33, 34, 36
13
37
86, 88, 89
12
184
14
167, 171
146, 149, 165
86
103
5
14
28, 30, 36
, 166, 170, 172
171
88, 89, 91
199
13
86
144
, 175, 182, 183
199
122
145
86, 88, 89, 90
74
14
9, 13
127, 128, 129,
127, 132, 145
13
14
86
173, 183
173, 183
144
210
-------
SUBJECT INDEX
Adel, Georgia
Aerated lagoons
Aeration
Aerators
static tube
surface
Aerobic decomposition
Aerobic stabilization lagoons
Aerobic wastewater treatment ponds
aerated ponds
photosynthetic ponds
retention ponds
Aesthetic failures
highly colored effluents
malodorous algae blooms
noxious vegetative growth
obnoxious hydrogen sulfide odors
septic sewage odors
Alley, Georgia 158, 159, 160, 161,
162, 164
Air floatation and filtration
Air temperature
Algae 42,
accumulation of metals
Anabaena flos-aquae
Astasia
97
3, 200
52, 53
70
70
70
93
75
4
4
4
4
6
6
6
6
64, 68, 71
28, 29
, 102, 120
Chlamydomonas sp.
Chlorella
Chlorophyta
clogging process
Cyanophyta
death
destruction
E. coli
generation rates
Microcystis flos-aquae
Motile
Oscillatoria
removal
respiration requirements
Scenedesmus
88, 92,
47, 92,
Algae cells lysis
Algal removal
chlorophyll extractions
detention time
dissolved air flotation
fluorometric technique
relative fluorescence
sand filtration
settling rates
suspension
techniques
Algal settling rates measurement
Algal suspended solids
Amendments
Ammonia
Ammonia concentration
116
113
92
167
92
47
173
47
47
112, 113, 116
47, 48
47
47, 92
175
72, 75
79
92, 93, 96
88
88
92, 93
72
76
114
15
79, 120, 174, 175
173
Anabena flos-aquae 10, 88
Anaerobic waste stabilization
pond (AWSP) 37
Application rates 149, 151
Aquaculture 64, 71
Aquaculture treatment systems 124
definition 120
Ash 115, 116
Ash content 119
Ash fraction 118
Astasia 88
Autoflocculation 75
Backwash filter 68
Bench scale studies 44
Bicarbonate 120
Biochemical oxygen demand 2, 6, 15, 38,
39, 41, 42, 43, 45, 46, 47, 48, 63,
64, 65, 66, 71, 75, 79, 80, 81, 92,
93, 101, 108, 109, 115, 118, 173
average effluent
demand
effluent
influent
loading rate
performance
22
112
81, 161, 162
81
109
20, 21, 149, 151, 152
pilot scale series 155
removal 26, 27, 117, 148, 149
187, 188, 189
removal efficiencies
actual 31
comparison 31
Biological oxidation 120
Biological disks, baffles, raceways 75
Biological harvesting 75
Biomass
algal 111, 112
grazer 111
Bixby, Oklahoma 200, 201
Blue Springs, Missouri 100
Brachlonus (Rotifers) 111
Burley, Idaho 64, 70
C
Cadmium
Calcium
California Water Resources
Control Board
Capital costs
Capital equipment
Carbon
Carbon dioxide
Carbonate
Cardiff aquacell demonstration
facility
design
biological components
9
120
105
184
184
120
120
120
136
138
211
-------
Center pivot unit 192, 194
flowrate vs. cost 194, 195
flowrate and land value
vs. cost 195
Center pivot spray irrigation 192
Centrif ugation 75
CH2M Hill 63, 64, 65
Chemical addition technology 11
Chemical coagulation 92
alum 92, 93, 101
ferric chloride 92
polyelectroly tes 92
Chemical oxygen demand (COD) 39, 43, 44,
45, 46, 48, 65, 79, 80, 112, 118,
173, 175, 177
total removal 116
Chlamydomonas sp. 88, 92, 116
Chloramines
dichloramine
monochloramine
nitrogen trichloride
toxic
Chlorella
Chlorella pyrenoidosa
Chlorella vulgaris
Chlorination
basic principles
experimental facilities
field study
Chlorination curves comparison
Chlorination systems
mixing and contact tanks
schematic
Chlorination unit
costs
Chlorinators
direct feed
vacuum feed
Chlorine
free
residuals
Chlorine dose
Chlorine supply
Chlorophyll
Chlorophyll a
removal
Chlorophyta
174
174
174
174
173
92, 113
9
9, 10
173
174
175
174
175
175
176
176
199
199
180
180
180
173
174, 175, 176
178
181
180
78, 79, 80
112, 113, 114, 115, 119
117
92
Chloroplast reorientation
Clean Water Act of 1972
(PL 92-500)
Clean Water Act of 1977
Climate
temperature
wind movement
Closterium
Coagulation-flocculation
Coarse screening
Coliform removal
Comminution
Composite-Sampler
Isco Automatic, Model 1580
Complete containment
Contact chambers
cleaning
hydraulic performances
outfall lines
solids removal
Conventional wastewater treatment
lagoons
limitations
75,
88
75
124
105
106
106, 116
119
168
167
178
167
108
75
178
181
178
180
180
125
Cost estimates
oxidation pond systems 184
Corrine, Utah 18, 19, 21, 23, 24, 27, 29,
30, 32, 34
Crop revenues 184
Gumming, Georgia 100
Cyanophyta 92
Cyclops (Copepods) 111
D
Daphnia 10, 111, 151
Davis, California, project 167
coarse screening 1-67
communication 167
cost 168
environmental impact 168
grit removal 167
pre-aeration 16?
prechlorination 167
primary sedimentation 167
Dechlorination 180
Department of Environmental Quality
(DEQ) 65, 70
Design criteria 24
organic loading 24, 26, 35
hydraulic detention time 24, 26, 35
Design load 18
Dichloramine 174
Diffusers 180
Dike protection and seepage control 52
Dilution restriction 66
Dimethyl sulfide 9
Disinfection efficiency 178
Dissiolved air
flotation (DAF) 75, 92, 93, 96, 101
Dissolved organic compounds 173
Dissolved oxygen analysis 79, 80
Drainage water
irrigation reuse 167
Dry weight determinations llli 116
Earthwork 52, 54
Effective size sand filters 154
Effluent
quality 6
Chlorination 6
Effluent BOD 28, 29
Effluent criteria 66, 70
Effluent limitations 16
Effluent samples 2
Effluent systems
applying to land 11
Effluents 104
discharge 109
facultative 105, 106, 108
isolation pond 108
oxygenated 104
prestrained 111
volumes 113
Empirical design equations 25
Environmental Protection Agency
research program 10
program objectives 10
program status 11
program costs 11
Eudora, Kansas 18, 19, 23, 24, 27, 29,
30, 32, 33
Evaporation 109, 113
212
-------
18,
Facultative lagoons
Facultative ponds
algal composition
depths
overflows no, in,
Facultative waste stabilization pond
Corrine, Utah
design
Eudora, Kansas
evaluation
Peterborough, N. H.
Fecal coliform
effluent
influent
performance
removal
Federal secondary treatment
standards
Federal Water Pollution Control
Act Amendments
interpretation of 304 (d)
of 1972
Federal Water Pollution Control Acts
PL 92-500
PL 95-217
Filter washing
cleaning
man-hours
raking
weed control
Floating macrophytes
advantages
disadvantages
Flocculation
Flowrate
instantaneous
Flushing meadows (Phoenix) Arizona
108, 111
112
109
112
19
33
19
18
19
15
31
31
23
23, 206
20, 151
51
51
155, 156
164
164
164
164
126
128
174
108
167
Gardendale, S. Carolina 97
Gas ehromatograph
techniques 9
Gas vacuole degradation 88
Gastrointestinal disorders 10
Gekeler slough 66, 70
Geotechnical investigation 52
Granular media filtration 75
Greenville, Alabama 98
Grit removal 167
Gronde Ronde River 66, 68, 70
Groundwater quality 1°7
Gulfport, Mississippi 201, 202
H
Hercules solar aquacell facility
aquatic plant by product reuse
design
plan
projected effluent quality
water by-product reuse
Heavy metals
High rate biological treatment
systems
Holding ponds
Hydraulic detention
Hydraulic detention time
actual values
design criteria 24
theoretical
44
39,
25, 26
18, 19
143
141
142
143
143
120
, 48
166
Hydraulic flow depth 18
Hydraulic loading rate 109, 113, 117,
149, 151, 155
Hydraulic performance 178
Hydraulics 52, 60
Hypochlorous acid 174
Tee formation 170
Infiltration-percolation 192
Influent BOD 28, 29
Influent COD 30
Influent flow rate 28, 29, 30
Integrated ponding 104, 105
design details 104
Intermittent sand filters 11
Intermittent sand filter system
Alley, Georgia 161
Moriarty, New Mexico 159
Mt. Shasta Lagoon 158
Intermittent sand filtration 75, 146,
149, 153, 168
effectiveness 165
series 153
washing 156
In-pond chemical precipitation 75
In-pond removal of particulate
matter 75
Integrated ponding 119
Interpond transfer systems 104
Irrigation 192
Irrigation discharge 68
summer 68
Irrigation district 68
Isobutyl mercaptan 9
Isolation cycle duration 117
Isolation pond 104, 105, 106, 10?
algal SS 113
chlorophyll 114
discharge 113
effluent 108
effluent suspended solids 113
chlorophyll 113
in situ 108
overflow composition 115
performance 117
studies 105
Isopropyl mercaptan 9
26
35
-20
K
Kilmichael, Mississippi
29, 30
Koshkonong, Wisconsin
Labor costs
Lagoons
aesthetic failures
disinfection
Lagoon effluent
chlorination
land application
Lagoon effluents
disinfection
disposal
filtration
land application
polishing
secondary
treatment
18, 20, 23, 24,
202
184
6
7
199
68
146, 173
173
166
154
68, 166
146
151
166
213
-------
upgrading 146, 165
Lagoon systems 3
Lagoon temperature 28, 30
Lagoon upgrading techniques 101
alternatives 66
design factors 70
evolution 64
history 63
technology 64
Lagoons
aerated 48
chemical treatment 69
design operation 166
early systems 166
filtration 69
selection 166
2-cell system 65, 70
LaGrande, Oregon 64, 65, 68
Lancaster, California 63, 68
Land application costs
center pivot spray irrigation 192
overland flow 192, 196
ridge and furrow 192
solid set sprinkler 192, 193, 194
Land application units
flowrate and application rate
vs. land requirements 191
flowrate and TDH vs. annual
energy cost 191
soil type vs. liquid loading 190
Land disposal 63
Land resale value 184
Land treatment 63, 64
Layout 52, 53
Leakage test 52, 61
Logan, Utah
centralized sewage treatment 51
M
Magnesium salts 120
Mechanically aerated pond (MAP) 37
Methane fermentation 120
Methyl mercaptan 9
Micractinium 121
10
Microcystis aeurginosa
Microcystis flos-aquae
Microscreening 5T7 71, 92, 93, 94, 96,
97, 98, 101
cost effective analysis
feasibility
pilot unit
polyester fabric
stainless steel media
Microstraining
Monochloramine
Moriarty, New Mexico
162, 163
Mount Shasta, California
161, 163
Municipal Environmental Research
Laboratory
Municipal wastewater
comparisons
Muskegon County (Michigan)
center pivot machines
drainage system
location
water budget
9 , 88
93, 101
71
92
92, 93, 95
92, 93, 95
64, 71, 75, 105, 121
174
158, 159, 160,
158, 159, 160,
192
168
168
168
168
168
Jl
Natural aeration
n-butyl mercaptan
Nitrate
Nitrate reduction
Nitrogen
Nitrogen trichloride
Nutrient control
technology
Nutrient stripping
0
Ontario, Oregon
Organic loading
Organic matter
Organic nitrogen
Organic shock loading
Oscillatoria 9, 112, 113,
119, 121
Oscillatoria tenuis
Outfall lines
Overland flow 168
flowrate and land value
vs. cost
flowrate vs. cost
Owasso, Oklahoma
Oxidation ditches
Oxidation pond systems
capital costs
cost estimates
energy costs
land costs
0 & M costs
Oxidation ponds
costs
definition
flowrate vs. annual costs
natural aeration
storage requirements
submerged aeration
surface aeration
use of
184, 185
9
79, 80
120
120, 168
174
10
104
64
24, 25, 26
146
79, 80
93
116, 118,
9
180
, 192, 196
197, 198
196
98
75
184
184
184
184
184
4, 10
11
4, 5
186, 187
184
185
189
189
4
Parameter units 28
Particulate BOD removal 78
Pawnee, Illinois 201
Peak flow 184
Percolation 109, 113
Peterborough, New Hampshire 18, 19, 23,
24, 27, 29, 30
Phase isolation 64, 65, 67, 104
multi-pond sequence 104
Phase isolation systems 11
Philippines 120
Photosynthetic oxygenation 120
Photosynthetic ponds
flow-through 16
Phosphorus 79, 80, 120
analysis 80
requirements 16
Piping and valves 180
Planning and design
deficiencies 169
Plectonema 119
Plug flow reactors 175
Polishing (aerobic) waste
stabilization pond (PWSP) 37
214
-------
Polishing lagoon effluents
Polishing units
dissolved air flotation
intermittent sand filters
microscreens
rock media filters
Pond area
Pond effluent
chlorination 173,
filtered
primary
secondary
unfiltered
Preaeration
Prechlorination
Preliminary treatments
capital costs
Pressure filter
Pretreatments
grit chamber and bar screens
Primary cell effluent
Primary sedimentation
Pumping efficiencies
_
Radiation energy
Rapid infiltration systems
Rational design equations
Raw sewage
domestic
f lowrate
inflow
loading
Receiving streams
effects of algae
Refactory organic materials
Regulatory standards
embankment and dike design
flow measurement
inlet outlet structures
isolation
pond bottom treatment
size
Relative humidity
Removal mechanism
rock filters
Richmond, California
Ridge and furrow irrigation
units
flowrate and application
rate vs. cost
flowrate vs. cost
Rigby, Idaho
Rock filters
field evaluation
Rock media filters
Roosevelt, Utah
Safety equipment
chlorine leak detection
exhaust fan
Safety precautions
Sampling and analysis
Sampling and analytical methods
Sand filter bed
Sand filtration
Scenedesmus
Secondary treatment standards
65, 66
146
192
199
192
199
192
28, 31
174, 178
178
175
175
178
167
167
185
96
184
29
167
184
38
167
30
108, 146
108
108
109
109
6
44
51
51
51
51
51
51
28, 29
76
92
192, 197
197
198
181
88
75
192
181
180
180
180
181
181
79
146
92, 93
92, 121
2, 63,
amendments 15
chemical addition (alum) 63, 64.
68, 71
clarification 63, 68
dual media filtration 63, 71
lagoons 5
ponds 6
regulations 15
requirements 5
revisions 7, 16
Sedimentation 84, 104, 168
algal 104, 105
Series intermittent sand
filtration 153, 154, 156
three-stage 156
Shock loadings 48
Single stage filtration 146, 148
performance 149
sand size effect 149
winter operation 149
Site reconnaissance 52
Slow sand filtration 146
Sludge
floating 109
Small communities 146
Sodium 167
Soil mantle disposal 75
Solana Beach Pilot Laboratory 135
operational results 136
system description 135
Solar aquacell process
advantages 129
bio-film substrates 132
designing 131
historical development 129
solar greenhouse pond cover 134
Solar radiation 28, 29, 30
Solid set sprinkler 192
Solid set sprinkler unit 192, 193
flowrate and land value
vs. cost 194
flowrate vs. cost 193
Solids removal 180
Specific conductance 167
Stabilization pond chlorination
examples
Rigby, Idaho 181
Roosevelt, Utah 181
Stockton, California 92
Structures 52, 61
Submerged aeration ponds 189
flowrate vs. annual costs 187, 190
flowrate vs. annual land
costs 188
Sulfide 175
analysis 79, 80
concentrations 177
Sunnyvale, California 92
Surface aeration 189
costs of 189
Sulfur compounds
odorus 9
Suspended solids (SS) 2, 92, 93, 101,
111, 112, 113, 115, 146, 148, 203,204
algal HI, 112, 116
average effluent 23
effluent concentration 163
grazer 111, 112, 114, 116
performance 22, 149, 150, 151, 158
pilot scale series 154
215
-------
reduction
regulations
removal
summary
total
volatile
Symploca muscorum
174
15, 16
6, 10, 117, 119, 205
153
79, 80, 111, 115, 116
79, 80, 111, 112, 116
9
Temperature
analysis 79
Thermal stratification 38
Total alkalinity 120
Total nitrogen 108, 109, 112, ]16, 118
removal 117
Total organic carbon (TOO 39, 43, 44,
46, 79, 80
Total suspended solids (TSS) 39, 41,
43, 44, 45, 48, 63, 64, 65, 66, 71,
78, 80, 81, 106, 111, 112, 118
effluent 81
influent 81
Treatment works
publicly owned 2
U
Utah State University
Upgrading lagoon effluents
methods
Upgrading lagoons
Upgrading techniques
algae laden effluents
intermittent sand filter
land application of
submerged rock filter
174
146
75
126
2
2
2
2
88
Veneta Lagoon
Veneta,. Oregon
rock filter 76, 77, 78
wastewater treatment system 77
Veneta rock filter 76, 77, 78
operational history 81
Volatile suspended solids (VSS) 46, 65,
111, 112, 115, 174
W
Wastewater lagoons 63, 72
Wastewater ponds 104
composition 105
overflowing 104
Waste stabilization pond systems
(WSPS) 37, 38, 39, 40, 48, 146
case history data 39, 41
comparison w/activated sludge 44,
45, 46
data analysis 39
model 41
FWSP (Facultative Waste
Stabilization Pond) 37, 38, 41
application limits 43
cost curve scale
factor 44
cost parameter 44
detention 47
effectiveness 42
major equipment 44
operating basis 43
residues 44
temperature 44
WSPS
economic considerations
45,
48
46
47
15, 37,
empirical designs
impact on waterways
Wastewater stabilization ponds
39, 72, 200
aeration 52, 53
construction 51, 52
design 51, 52
dike protection 52
earthwork 52, 54
geotechnical investigation 52
hydraulics 52, 60
layout 52, 53
leakage test 52
major biological reactions 37
regulatory standards 51
secondary requirements 15
site reconnaissance 52
structures 52, 61
Water rights 68
Water supply 105
chemical analysis 107
Wind speed 28, 29
Windber, Pennsylvania 202
Woodland, California 64, 105, 108
climate 105, 106
overflow 110, 115
pond isolation studies 105
ponding system 105, 107
raw sewage 108, 109
sampling schedule 108
suspended solids 111, 113, 115
water supply 105, 107
Woodland ponding system 118
Zooplankton 151
Zern Industries, Inc. 71
216
-------
/PI TECHNICAL REPORT DATA
jriease read Instructions on the reverse before completing
EPA-600/9-79-011
. TITLE AND SUBTITLE
PERFORMANCE AND UPGRADING OF WASTEWATER STABILIZATION
PONDS; Proceedings of a Conference Held August 23-25,
1978, at Utah State University, Logan, Utah
6. PERFORMING ORGANIZATION CODE
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
May 1979 (IssuIng Date)
UTHOR(S)( Editors)
E. Joe Middlebrooks, Donna H. Falkenborg, and
Ronald F. Lewis
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Utah Water Research Laboratory
Utah State University
Logan, Utah 84322
10. PROGRAM ELEMENT NO.
1BC611
11. CONTRACT/GRANT NO.
R805842
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Cin.
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
OH
13. TYPE OF REPORT AND PERIOD COVERED
Final, 1978
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Project Officer: Ronald F. Lewis (513) 684-7644
16. ABSTRACT
The proceedings contain 18 papers discussing and describing the design,
operation, performance and upgrading of lagoon systems. Performance data for
facultative and aerated lagoons collected at numerous sites throughout the USA
are presented. Design criteria and the applicability of performance data to design
eouations are discussed. Rock filters, intermittent sand filters, microscreening
and other physical-chemical techniques, phase isolation, land application, and
controlled environment aquaculture were evaluated as methods applicable to up-
grading lagoon effluents. The proceedings conclude with a presentation on the
costs associated with the construction, operation and maintenance of lagoon
systems.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a.
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Wastewater
Lagoon (ponds)
Effluents
Algae
Separation
Proceedings
13B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
IO. OF PAGES
223
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77)
217
U. S. GOVERNMENT PRINTING OFflCE: 1979-657-060/1657 Region No. 5-11
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