United States
Environmental Protection
Agency
'Municipal Environmental Research
Laboratory
Cincinnati OH 45268
EPA-600/2-80-155
August 1980
Research and Development
&EPA
Field Study of
Nutrient Control in a
Multicell Lagoon
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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 report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from poipt and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This.document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-80-155
August 1980
FIELD STUDY OF NUTRIENT CONTROL IN A MULTICELL LAGOON
by
William T. Engel
Thomas T. Schwing
Charles County Community College
La Plata, Maryland 20646
Grant No. R803637
Project Officer
Edward J. Opatken
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI,.OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research Laboratory, U. S. Environmental
Protection Agency, and approved for publication. Approval does not signify 'that the contents necessarily reflect
the views and policies of the U. S. Environmental Protection Agency, nor does mention of trade names or commer-
cial products constitute endorsement or recommendation for use.
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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 that environ-
ment and the interplay of 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 pro-
blem, measuring its impact, and searching for solutions. The Municipal Environmental Research Laboratory devel-
ops new and improved technology and systems for the prevention, treatment, and management 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 for the minimization of adverse economic, social, hygienic, and
aesthetic effects of pollution. This publication is one of the products of that research and provides a most vital
communications link between the research and the user community.
This study was conducted in order to develop reliable techniques for removing phosphorus from lagoon
effluents. The potential for achieving consistent nitrification using a plastic-media, trickling filter tower was also
evaluated.
Francis T. Mayo
Director
Municipal Environmental Research Laboratory
111
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ABSTRACT
Lagoons are well known as acceptable methods of treating both municipal and industrial wastes. The more
stringent Federal Discharge Standards have caused Ithe systems to be re-evaluated in terms of efficiency. Modifica-
tions to existing facilities appear feasible. This report studied nutrient removal in a serially arranged, multicell,
aerated, facultative lagoon system over a 3-year period.
i
The general objective of this study was to develop reliable techniques for removing phosphorus from lagoon
effluents. The potential for achieving consistent nitrification using a plastic-media, trickling filter tower was also
evaluated.
A six-cell lagoon system was modified in order to have two independent three-cell systems, one of which
was to be the control and the other the test. Each system contained ah aerated first cell. Alum addition to the third
cell of the test system proved to be more efficient in removing total phosphorus as well as BOD and suspended
solids, than alum addition to the first cell. f
A plastic-media, trickling filter tower was installed at the effluent station of the third cell of the test
system. Consistent nitrification was established; however, seasonal effects caused the system to be less efficient dur-
ing the winter months.
Lagoons that have been modified to implement these forms of nutrient control should be considered as
viable, economic means of meeting current secondary standards.
This report was submitted by the Charles County Community College in fulfillment of Grant No. R803637,
sponsored by the U.S. Environmental Protection Agency. It covers the period July 1, 1975, to September 30,
1978, with all work completed by June 30, 1979.
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CONTENTS
Foreword. . . : . ijj
Abstract .• ' .' jv
Figures ; vi
Tables vijj
Abbreviations jx
Acknowledgments xi
1. Introduction 1
Primary Objectives i
Secondary Objectives 1
2. Conclusions . . 2
3. Recommendations 4
4. Literature Review * 5
5. Experimental Methodology ; 7
Study Location. . • . 7
Lagoon System 7
Study Procedures j2
Phosphorus Study . j 3
Nitrification Study jg
Sample Collection and Analysis jp
Apparatus , . 24
Analytical Procedures 24
Meteorological Data ' , . 24
Data Analysis 27
Algae Analysis 27
6. Results and Discussion 28
Background Data Study 28
Phosphorus Study . 38
Nitrification Study 51
Microbiological Correlation 54
Economical Considerations 66
7. Summary 67
References
68
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FIGURES
8
8
9
9
10,
13
14
Number Page
1 Aerial photograph - St. Charles LagooniSystem
2 Lagoon operation prior to 1969 ; •
3 Serial flow pattern prior to study ....;..., • • •
4 Lagoon study area (A, C, D test system; B, E, F control system).
5 Effluent system •
6 Schedule of project tasks ;
7 Storage and handling facilities for alum •
8 Chemical contact chamber •'•"• •" 15
9 Tower location 18
10 Tower piping . • • • 19
11 Study area with sampling stations ....."...- 20
12 Automatic effluent sampler 22
13 Transfer vault with sampler v; .'.... 23
14 Sampler drum unit 23
15 BOD, raw influent and Cell B effluent , 29
16 BOD, raw influent and Cell E effluent 30
17 BOD, raw influent and Cell F effluent. 30
18 Probability of BOD remaining in the control system. 31
19 Suspended solids, raw influent and Cell B effluent . 32
20 Suspended solids, raw influent and Cell E effluent 32
21 Suspended solids, raw influent and Cell F effluent. . . 33
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Number Page
22 Probability of suspended solids removal in the control system 34
23 Ammonia of raw influent and effluent for Cells B, E and F (stations 1, 2, 3 and 4) 35
24 Nitrite/nitrate of raw influent and effluent of Cells B, E and F . 36
25 Total phosphorus of raw influent and effluent of Cells B, E and F 37
26 Soluble phosphorus of raw influent and effluent of Cells B, E and F 38
27 Test and control system 39
28 BOD and suspended solids - Cell D (Station 7) 41
29 Ammonia of raw influent and effluent of Cell D 42
, 30 Total phosphorus of raw influent and effluent of Cell D , 43
31 Soluble phosphorus of raw influent and effluent of Cell D 43
32 BOD and suspended solids Cell A (Station 5) 46
33 Ammonia of raw influent and effluent of Cell A 47
- j •
34 Total phosphorus of raw influent and effluent of Cell A • •. ., 48
35 Total phosphorus versus Al/P ratio in Cell A '. 49
36 Soluble phosphorus of raw influent and effluent of Cell A 50
37 BOD tower influent and effluent 54
38 Total algae counts for the test system 55
39 Total algae counts for the control system 56
40 Density of Euglena in the control system 57
41 Density of Euglena in the test system 57
42 Population dynamics of green motile forms in the test system 59
43 Population dynamics of green motile forms in the control system 59
44 ; Population densities of nonmotile green algae in the test system • • • • • 62
45 Population densities of nonmotile green algae in the control system 62
46 Densities of blue-green algae for the control system , . . 63
47 Densities of blue-green algae for the test system 63
vii
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TABLES
Number Page
1 Influent and Effluent Flows (Total) 11
2 Test and Control System Effluent Flows . . . f 12
3 Composition of Liquid Alum 14
4 Sampling Program •, 21
5 Methods and Special Laboratory Equipment 25 .
6 Control Lagoon System Yearly Averages 28
7 System A-C andB-E Comparison (%Efficiency).-. . . — 39
8 Control System and Test System (% Efficiency) 39
9 Test Lagoon System Yearly Averages 40
10 Test Lagoon System Yearly Averages . , 45
11 Al/P Ratios and Dosage Rates for Cell A . . . . 49
12 Tower Influent and Effluent Data. 51
13 Tower Influent and Effluent Relationships for BOD and Suspended Solids. 52
14 Tower Influent and Effluent Relationships for Organic Nitrogen 53
15 Total Algae - Average Units/mB i 55
16 Evglena - Average Units/ma ' 58
17 Motile Green Algae - Average Units/mE .' 60
18 Phytoplankton Genera Identified ....;.. 61
19 Nonmotile Green Algae -Average Units/mE . 64,
20 Blue-Green Algae - Average Units/me ,. . . 65
vm
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LIST OF ABBREVIATIONS
Alk
Alum
Avg
BOD
COD
cm
DO
ft
g
gal
gpm
GM
ha
in.
kcal
kg
km
Ib
m
mg
acre
alkalinity - the sum of the bicarbonate, carbonate, and hydroxide ions expressed as CaCoj
mg/e
filter alum - A12(SO4)3 • 14H20(aq)
average
5-day, 20°C, biochemical oxygen demand, mg/E •
chemical oxygen demand, mg/2
centimeter . •
dissolved oxygen, mg/fi
feet
gram
gallon
gallon per minute
geometric mean
hectare •.,••,
inch
kilocalorie - •
kilogram . .
kilometer
pound , :
meter
— milligram
IX
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mi
mg/fi
MGD
MPN
NH3N
NOAA
NO2*/NO3-
OA.H.
Phos
qt
rpm
sec
SS
S04S
Sol
StdDev
Temp
TKN
Tot
Vol
Yr
mile
milligram/liter
million gallons per day
most probable number
ammonia nitrogen (mg/fi)
National Oceanographic and [Atmospheric Administration
nitrite-nitrate (mg/fi)
outside average height
phosphorus
quart
revolutions per minute
second
suspended solids
sulfate
soluble
standard deviation
temperature
total Kjeldahl nitrogen
total
volatile
— year
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ACKNOWLEDGMENTS
This research project was initiated in 1975 under the direction of Mr. Carl M. Schwing, who is currently
Director of Municipal Utilities in Galveston, Texas. His advice and expertise have been extremely helpful, not only
during the field work but also throughout the formulation of this report.
The cooperation, assistance, and contribution of St. Charles Communities in Waldorf, Maryland are greatly
appreciated. Mr. Paul Corn, Director of St. Charles Utilities, expended much time and effort in the project's behalf.
Sincere thanks are extended to the following individuals who were involved in this project and who contri-
buted significantly to its completion:
Edward J. Opatken - Project Officer, U.S. Environmental Protection Agency
J. N. Carsey, Ph.D. - President, Charles County Community College
John H. Highby - Assistant Professor of Chemistry; Part-time Field Technician; Member of the
Review Team
Ted Lufriu - Lab Technician; Graphics Artist; Member of the Review Team
Bill McDonald - Field Technician; Text Writer; Member of the Review Team
Justine Herring - Administrative Assistant; Report Coordinator; Computer Operator; Member of
the Review Team
Terri Sullivan - Secretary
Jean Jones - Report Typist
Richard Siciliano - Editor
Eileen Schmidt - Technical Editor
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SECTION 1
INTRODUCTION
During the last 25 years, lagoons (wastewater stabilization ponds) have gained increasing popularity as an
economically attractive method of wastewater treatment for small and emerging population centers. However, their
ability to consistently meet the secondary treatment standards promulgated by the Federal Water Pollution Control
Act Amendments (P. L. 92-500) is in question. The Clean Water Bill of 1977 (1), raised certain limits of lagoon
standards. For example, the effluent limits for suspended solids in lagoons for the State 'of Maryland have been
changed from 30 mg/E to 90 mg/fi (2).
In contrast to their increased usage since 1940, lagoons have received relatively little attention from the
engineering community. The complex and uncontrolled character of the lagoon treatment process presents an in-
herently difficult problem to study. Thus, useful data are not easily generated. Since lagoons are simple to operate,
they do not require the attention of an operator on a regular basis. As a result, operational data collected prior to
1972 was amassed slowly and without the benefit of an overall plan with specific objectives.
In 1973, the U.S. Environmental Protection Agency (EPA) began a program to formalize and upgrade
lagoon technology. Its objective was to determine the viability of the lagoon • as a secondary treatment process,
capable of meeting Federal and State effluent quality standards. This program incorporated studies of several lagoon
systems throughout the United States. Each study was directed to assess a specific problem or set of problems. The
St. Charles Communities lagoon system located in Waldorf, Maryland, was selected as one of the research sites. Using
this system, the Charles County Community College, La Plata, Maryland, conducted a 3-year study, whose clearly
defined objectives are outlined as follows:
1. To develop reliable techniques consistent with the basic simplicity of lagoon operation for removing
phosphorus and unoxidized nitrogen from lagoon effluents.
2. To evaluate the potential for achieving consistent nitrification by using a plastic media, trickling filter
tower that will treat a sidestream of effluent from the last cell of the test series.
SECONDARY OBJECTIVES
1. To generate reliable, long-term performance data on a three-cell combined, aerated-facultative lagoon
which does not have alum added, which is operated in parallel with the test system, and which serves
as a control.
2. To assess the effect of alum addition, not only on phosphorus removal but also on suspended solids
; and organic removals.
3. To determine the additional costs and operating requirements necessitated by the nutrient control
procedures.
The results presented in this report were obtained from data collected over a period of 36 months. Fifteen
parameters were studied at nine key sample locations.
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SECTION 2
CONCLUSIONS
1. Statistical analysis indicated that the first two cells of the test and control systems performed comparably.
2. Statistical analysis indicated that the first [two cells of the system produced an effluent similar in water
quality to the three-cell system. I
3. The effluent from the first two cells of the three-cell system whose first cell is aerated met the existing
secondary standard of 30 mg/e for BOD. ;
4. The majority of soluble BOD was converted ;to insoluble BOD in the aerated first cell.
5. Very little conversion of soluble BOD to insoluble BOD occurred in the second and third cells.
6. The secondary BOD standard of 30 mg/e could be met when alum was added to the third cell of the three-cell
test lagoon system. . ;
7. Alum addition to the third cell of a three-cell system is more efficient in removing BOD and suspended solids
than alum addition to the first cell of the system.
8. A two- or three-cell system whose first cell is aerated did not meet the existing secondary standard of 3 0 mg/e
for suspended solids.
9. A two- or three-cell system whose first cell is aerated will meet the existing State of Maryland effluent lagoon
standard of 90 mg/e for suspended solids.
10, The suspended solids standard of 30 mg/e could not be met consistently when alum was added to the third
cell of the test system; however, the state of Maryland standard of 90 mg/e was met consistently.
11. The secondary standard of 200 MPN/100 me for fecal coliform could not be achieved without chlorination
of the three-cell lagoon effluent,
12. The three-cell lagoon system produced an ayerage total phosphorus concentration of 6.6 mg/e and an average
soluble phosphorus concentration of 5.8 mg/e in the final effluent.
13. The addition of alum to the final cell of the three-cell test lagoon system produced an annual total phosphorus
concentration of 2.5 mg/B and a soluble phosphorus concentration of 1.6 mg/e in the final effluent. This
represents an 81% reduction in total and an 85% reduction in soluble phosphorus.
14. The addition of alum to the first cell of a three-cell system produced an annual total phosphorus concentra-
tion of 4.1 mg/e and a soluble phosphorus concentration of 3.2 mg/e. This represents a 60% reduction in
total and a 75% reduction in soluble phosphorus concentrations.
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15. Alum addition to the third cell of a three-cell system produced lower total and soluble phosphorus concen-
trations in the final effluent than alum addition to the first cell of a system.
16. The highest ammonia reduction occurred in the aerated first cell.
17. The nitrite/nitrate concentration did not increase significantly after the first aerated cell.
18. A nitrification tower performed at an efficiency of 83% i 2% on the effluent of a three-cell lagoon system.
19. Increases in pH, temperature, and DO led to increased nitrification. ,
20. The acid content destroys alkalinity at a ratio of 6.9 mg CaCO3/1.0 mg NHj.
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SECTION 3
RECOMMENDATIONS
1. A three-cell lagoon system should be studied to determine the efficiency of batch- versus continuous-chemical
addition for phosphorus removal.
2. The feasibility of using slow- and high-rate sand filters for upgrading three-cell lagoon effluents to meet the
secondary standard of 30 mg/e suspended solids should be evaluated.
.1
3. In lagoons with seasonal- or batch-discharge, flow meters should be installed on the influent and effluent
lines to improve monitoring of the true loadings into the system.
4. The use of a mechanical clarifier to settle the chemical floe should be evaluated on the alum-treated effluent
in lieu of a third cell.
5. Annual performance evaluations of the overall efficiency of a lagoon system, as well as the individual cell
efficiencies, should be conducted to establish a bank of control data and identify problem areas affecting
performance.
6. Lagoon designs should provide for representative sampling of influent, intralagoon transfers, and effluent
streams.
7. The use of a nitrification tower on the effluent of a three-cell lagoon system to which no alum has been added
should be evaluated.
8. The feasibility of a settling mechanism for the removal of solids in the tower effluent should be studied.
9. Since the final effluent of this lagoon system is disposed of by spray irrigation,
a. the effect of an alum-treated effluent in aland treatment operation should be studied; and
i
b. the effect of a nitrified-lagoon effluent in1 a land treatment operation should be studied.
10. Considering the popularity and economic operating cost of lagoons, the data compiled in this project should
be used in setting attainable effluent limitations and adequate design guidelines.
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SECTION 4
LITERATURE REVIEW
Wastewater stabilization ponds have been used extensively as a means of treating wastewater. These ponds
have been defined as "basins natural or artifical, designed or used to treat organic waste by natural biological, bio-
chemical, and physical processes." (3) The concept appears to have evolved from practices associated with land
disposal of sewage effluents in areas with semi-arid and arid climatic conditions. It was riot until the 1920's that his-
tory first recorded information on ponds being used for wastewater treatment. After World War II, wastewater treat-
ment lagoons were accepted as a dependable engineered system for the treatment of municipal and industrial wastes
in the United States.
Prior to the enactment of the 1977 secondary treatment standards, EPA believed that the majority of
existing lagoon systems would fail to meet the new requirements. This feeling was based on the paucity of concrete
performance data indicating existing lagoons could meet the new standards and on Barsom's comprehensive report
on lagoon performance (4). Barsom evaluated data on 3,000 lagoon systems from 50 States and concluded that the
suitability of lagoons as secondary treatment systems was highly questionable.
Previous government-funded lagoon studies included those completed by Barsom (4), as cited above,
Champlin (5), and Christiansen (6). Although these earlier programs provided much needed information on lagoon
systems, they failed to deal effectively with the problems of poor lagoon design and inadequate lagoon treatment
technology. These problems were addressed at the symposium held at the Utah State University (7) in August 1974,
and as a result, EPA launched a program to upgrade existing lagoon systems to meet new discharge standards.
The objectives of the upgrading program were to be accomplished by providing guidelines developed
through major research in the following areas: low-cost suspended solids and algae removal, nutrient control, ef-
fluent discharge to the land, and disinfection and control of weeds and other undesirable growth.
Lagoon Performance
A major concern in the program was the general lack of long-term performance data on existing lagoon
systems. To provide this needed information early in the program, several Environmental Protection Agency-funded
studies were initiated during 1974 at different climatic regions in the United States. These studies were designed
specifically to generate prospective long-term performance data and to determine whether existing, well-designed,
continuous-discharge, multicelled lagoons would be able to meet the 1977 discharge standards.
The results of these studies did not entirely confirm earlier negative feelings regarding the adequacy of
lagoons as secondary treatment facilities. Reynolds et al. (8) evaluated a seven-celled lagoon system in Corinne,
Utah, and determined that the Federal secondary standard of 30 mg/fi BOD5 and 30 mg/e suspended solids were
met 100% and 70% of the time, respectively. Bowen (9), in studying a three-celled lagoon system in Peterborough,
New Hampshire, showed that secondary standards for 6005 and suspended solids were consistently met except for
an 11-week winter period when the BOD5 averaged 45 mg/8. McKinney (10), in evaluating a three-celled lagoon in
Eudora, Kansas, concluded that the system could not meet EPA standards because of excessive suspended solids in
the final effluent.
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Nutrient Control
In addition to more stringent secondary standards, major efforts are being directed toward nutrient control
in wastewatcr effluents. The eutrophication of receiving water systems is greatly accelerated when compounds of
phosphorus and nitrogen are introduced in excessive amounts. Nitrogen in the form of ammonia interferes with
chlorination and exerts a considerable oxygen demand on receiving systems. Under ideal conditions, excessive
nutrient input may result in massive algal blooms followed by extensive fish kills and the destruction of other
aquatic organisms. In an effort to help preclude these adverse effects, major research has recently been initiated
to develop nutrient control technology. ;
Phosphorus Removal
Until recently, technology in phosphorus removal has been developed mainly through research at conven-
tional treatment plants. This has traditionally been conducted by studying the effects of the addition of various
coagulants at different points in the treatment system. Technological developments dealing specifically with the
removal of phosphorus from lagoon effluents are few. Many reports on phosphorus removal in lagoons are only
byproducts of major research on algae removal by addition of coagulants.. Shindala and Stewart (11) studied the
application of several coagulants on a post treatment process to remove algae and improve the quality of effluents
from lagoons. They concluded that the optimum dosage for best removal of the parameters studied was 75 to 100
mg/fi of alum. They also presented a model to relate the degree of phosphate removal to coagulant dosage. Dis-
cussions at the Sixth Mississippi Water Resources Conference (12) resulted in the opinion that chemical coagula-
tion was effective in removing algae and phosphorus from lagoon effluents. In addition, alum was determined to
be the most effective coagulant.
In recent years, the Canadian Ministry of the Environment has demonstrated great concern in nutrient
removal from lagoons by initiating extensive research in this field. In an investigation on phosphorus removal from
lagoons, Graham and Hunsinger (13) concluded that batch-chemical treatment of seasonal retention lagoons with
alum or ferric chloride was an effective means of reducing the total phosphorus in pond effluent to below 1.0 mg/fi.
Boyko and Pupke (14) have discussed the problems and design considerations derived from full-scale research on
phosphorus removal from lagoons and conventional treatment plants. Included in their report are operational results
of past studies. • • •
Nitrification
Nitrification of wastewater does not remove nitrogen but converts ammonia to nitrites and nitrates. The
primary advantage to this process is an overall reduction in the total oxygen demand exerted on the receiving water
system. Numerous studies have been conducted on nitrification and technology has expanded to include the com-
bined carbon-oxidation-nitrification process and the separate-stage nitrification process. Both of these processes may
be further categorized as suspended-growth processes or attached-growth processes.
Recent research on the nitrification of lagoon effluents using a plastic-media trickling filter is limited. The
most comprehensive report available on nitrification utilizing a plastic-media trickling filter was conducted at a
conventional treatment plant by Duddles and Richardson (15). They found that plastic-media trickling filters are
capable of achieving consistent, high-level nitrification (>90%) when the tower influent contained 15-30 mg/fi BOD5
and ammonia concentration in the range of 10-20 mg/fi. They reported that the system produced consistent and
Stable performance during both summer and winter climates. Stone et al. (16) studied nitrification using a plastic-
media trickling filter at the Sunnyvale, California, oxidation ponds; however, they only reported surface area require-
ments to achieve a certain ammonia concentration in the effluent.
Borchardt et al. (17) initiated a nitrification study at Genoa, Ohio, utilizing a rotating biological disc in a
two-stage, flow-through lagoon. However, this investigation was discontinued because of high algae densities, low
NHj concentrations, precipitating calcium carbonate, and low environmental temperatures.
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SECTION 5
EXPERIMENTAL METHODOLOGY
STUDY LOCATION ,
The study was conducted at the St. Charles Communities wastewater lagoon system, Waldorf, Maryland.
St. Charles Communities is located in Charles County, Maryland, approximately 40 km (25 mi) south of Washington,
D.C. The community is a model city, privately developed by Interstate General Corporation and partially funded by
a Housing and Urban Development grant.
The community has a population of 8,000 and covers an area of approximately 3,200 ha (8,000 a). There
are a variety of housing models including single, duplex and triplex houses as well as townhouses, multiresidential
apartments and condominiums. The community is sectioned with neighborhood centers. Nonresidential structures
include schools, churches, service stations, food marts, and a library. In addition, there is an industrial park with
light manufacturing and service oriented companies.
On September 1, 1978, there were 1,758 connections to the water and sewer system. These consisted of:
1733 Simplex Houses
18 Duplex Houses
5 Nonprofit
2 Industrial
All triplex, townhouses and apartments are connected to the new lagoons (Cells G, H, and I). All simplex and
triplex dwellings constructed since 1975 (other than those listed above) were connected to the new lagoons.
The average water consumption was 79.7 m3 (21,048 gal) per residence per month for the period November
1, 1978, to January 31, 1979.
LAGOON SYSTEM
. The St. Charles lagoon system consists of nine cells as depicted hi Figure 1. Cells A, B, and C were con-
structed in 1966 and Cells D, E, and F were constructed in 1969. The cells indicated as G, H, and I were constructed
in 1971.
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Figure 1. Aerial photograph—St. Charles Lagoon System.
This study utilized Cells A through F. Although all nine cells can be interconnected, Cells A through F and Cells G,
H, and I have been historically, and were for the duration of this study, operated as separate systems. Influent to
the two lagoon systems originates indifferent neighborhoods in the St. Charles Communities.
The lagoon system under study was designed for either parallel or series operation between the six cells.
Prior to the 1969 lagoon expansion, Cells A, B, and C were operated as depicted in Figure 2.
Discharge
Figure 2. Lagoon Operation prior to 1969.
After the 1969 expansion, Cells A and'B iwere operated in parallel, followed by serial operation of Cells
C through F as depicted in Figure 3.
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iCell C ^
. i
Cell A
\
\
\
CellB
T
1
*• ceii b
1
Cell F -
1
I i
Cell E
Influent line
>•
^Effluent
jto spray
! irrigation
Figure 3. Serial flow pattern prior to study.
During this study, the system was operated so that there were two, three-cell parallel systems. Cells A, C, and D were
the test system, and Cells.B, E, and F served as the control system. Each system has a total surface area of 4.04 ha
(10 a). The average depth of all the ponds is approximately 1.22 m (4 ft). The flow pattern through each system and
the size of each are represented in Figure 4.
Cell C
i
(5 acres)
L
&
Cell A
^(3 acres)
Ce,,B^
^(2 acres)'
CellD
(2 acres)
Cell F
(T
(3 acres) [^
*•
CellE
[5 acres)
"Chlorine
Contact Tank
Influent line
I Aerators
Figure 4. Lagoon study area (A, C, D-Test system; B, E, F-Control system).
The design of Cells A through F was based on a projected population of 6,000 and a flow of 2,300 m3/day
(0.6 MGD), Based on the design flow and assuming equal flow distribution, the average detention time for each
system is 54 days.
Both Cells A and B have three, floating 5-horsepower, mechanical aerators which were installed during the
1969 expansion. Each aerator has an oxygen transfer rate of 2.7 kg/hr (6 Ib/hr). The aerators operate 24 hours per
day annually, except during periods of severe freezing.
The test and control systems are fed from a common influent pump station located approximately 540 m
(1,800 ft) from the treatment site. The influent flow into the lagoon system was calculated using elapsed time meters
and raw wastewater pump capacities. The influent receives no preliminary treatment before entering Cells A and B.
Effluent disposal is by land application through spray irrigation and is operated for approximately 7 hours
per day. During periods of cold weather, spray irrigation is restricted to sunlight hours. The water level is permitted
to rise in the cells until seasonal weather conditions permit discharge.
-------
During this study the effluent from the control system flowed into the chlorine contact tank for final
disposal. (See Figure 5.) The effluent from the test system passed from Cell D into Cell F for final discharge during
• r
Cell 1
6o| ^^
II i
CellD
[CellF »
P
^
r-
j 4
i -r-
^— ' '"'
•-*•" j F
Chlorination
Building
o Spray
rigation
ields
1 Chlorine |
D Pump contact ,
oo Flow Meter chamber
txt Valve
Effluent ;•
Chlorinated Effluent
Figure 5. Effluent system.
I
the first 12 months of the study, September 1975 to September 1976. Subsequent to September 1976, the effluent
of the control system was pumped from the southwest corner of Cell D by two, 1.7-m3/day (460-gpm) Hydromatic
submersible pumps, Model 5H200, which were connected in parallel to a common discharge header.
The effluent from Cell D could either be pumped to Cell I or to the chlorine contact tank at the end of
Cell F as shown in Figure 5.
Two propeller flow meters were located at the pump station in the chlorine contact chamber and recorded
the total discharge from Cell F. One, 20-cm (8-in), Badger propeller flow meter was located in the effluent line from
Cell D and recorded the total discharge from the test system. Tables 1 and 2 show all influent and effluent flow
values for the project.
10
-------
TABLE 1. INFLUENT AND EFFLUENT FLOWS (TOTAL)
Year/Month
1975/July
Aug
Sep
Oct
Nov
Dec
1975 Average
1976/Jan
Feb
Mar
Apr
May
June
July
Aug
Sep
Oct
Nov
Dec
1976 Average
1977/Jan
Feb
Mar
Apr
May
June
July
Aug
Sep
Oct
Nov
Dec
1977 Average
1978/Jan
Feb
Mar
Apr
May
June
July
Aug
Sep
1978 Average
Total MG
47.2
16.1
17.8
20.1
16.4
16.0
17.3
19.0
11.3
18.7
18.1
17.4
15.5
15.4 .
16.5
16.4
19.0
19.2
20.0
17.2
20.3
17.4
20.2
20.2
22.0
19.3
19.8
21.9
15.4
16.2
18.9
22.8
20.9
30.8
24.1
28.2
23.8
33.6
23.9
23.7
23.8
20.8
25.9
Influent
(rr.3)
(65,102)
(60,939)
(67,373)
(76,079)
(62,074)
(60,560)
(65,355)
,(71,915)
(42,771)
(70,780)
(68,509)
(65,859)
(58,668)
(58,289)
(62,453)
(62,074)
(71,915)
(72,672)
(75,700)
(65,134)
(76,836)
(65,859)
(76,457)
(76,457)
(83,270)
(73,051)
(74,943)
(82,892)
(58,289)
,(61,317)
(71,537)
(86,298)
(73,934)
(116,578)
( 91,219)
(106,737)
( 90,083)
(127,176)
( 90,462)
( 89,705)
, ( 90,083)
( 78,728)
( 97,863)
Avg. MGD
.556
.519
.593
.649
.548
.515
.563
.613
.391
.604
.602
.560
.518
.499
.532
.546
.613
.641
.646
.564
.656
.622
.651
.674
.707
.642
.638
.705
.514
.523
.631
.734
.641
.994
.861
.909
, .794
1.084
.799
.763
.766
.694
.852
(m3/d)
(2104)
(1964)
(2245)
(2457)
(2074)
(1949)
(2132)
(2320)
(1480)
(2286)
(2278)
(2120)
(1961)
(1889)
(2013)
(2066)
(2320)
(2426)
(2445)
(2134)
(2483)
(2354)
(2464)
(2551)
(2676)
(2430)
(2415)
(2668)
(1945)
(1980)
(2388)
(2778)
(2165)
(3766)
(3258)
(3440)
(3005)
(4103)
(3024)
" (2888)
(2899)
(2627)
(2683)
Total MG
20.9
18.9
20.4
24.8
" 18.3
18.2
20.3
12.4
18.8
20.9
23.0
20.8
15.8
16.9
17.8
20.8
18.8
20.9
15.0
18.5
16.1
16.8
23.9
17.5
20.2
19.1
NA
19.8
16.2
14.0
19.0
24.6
18.8
25.5
25.5
26.6
18.8
25.0
22.5
21.6
20.5
19.1
22.8
Effluent
(m3)
(79,107)
(71,537)
(77,214)
(93,868)
(69,266)
(68,887)
(76,647)
(46,934)
(71,158)
(79,107)
(87,055)
(78,728)
(59,803)
(63,967)
(67,373)
(78,728)
(71,158)
(79,107)
(56,775)
(69,991)
(60,939)
(63,588)
(90,462)
(66,238)
(76,457)
(72,294)
NA
(74,943)
(61,317)
(52,990)
(71,915)
(93,111)
(71,296)
( 96,518)
( 96,518)
(100,681)
( 71,158)
. ( 94,625)
( 85,163)
( 81,756)
( 77,971)
( 72,294)
( 86,298)
Avg. MGD
.675
.609
.679
.801
.609
.588
.660
.401
.673
.676
.767
.672
.528
.545
.575
.693
.783
.698
.471
.624
.518
.601
.772
.582 ,
.657 .
.637
NA
.710
.541
.453
.635
.794
.627
.821
.910
.859
.628
.805
.750
.696
.663
.637
.752
(m3/d)
(2555)
(2305)
(2570)
(3032)
(2305)
(2226)
(2499)
(1518)
(2547)
(2559)
(2903)
(2544)
(1998)
(2062)
(2176)
(2623)
(2963)
(2642)
(1782)
(2360)
(1960)
(2275)
(2922)
(2203)
(2486)
(2411)
NA
(2800)
(2048)
(1715)
(2403)
(3005)
(2384)
(3107)
(3444)
(3251)
(2377)
(3047)
(2839)
(2634)
(2509)
(2411)
(2847)
11
-------
TABLE 2. TEST AND CONTROL SYSTEM EFFLUENT FLOWS
Test System i
year/Month
1976/Sep*
Oct.
1976 Average
1977/July"
Aug
Sop
Oct
Nov
Dec
1977 Average
1978/Jan
Feb
Mar
Apr
May
June
July
Aug
Sop
1978 Average
Total MG
8.7
9.0
8.6
0.8
5.6
5.8
2.8
6.3
7.6
4.8
6.9
13.5
16.6
8.2
13.9
14.1
11.5
14.7
12.1
12.4
(m3)
(32,930)
(34.065)
(33,496)
( 3,028)
(21,196)
(21,953)
(10,598)
(23,846)
(28,766)
(18,231)
(26,117)
(51,098)
(62,831)
(31,037)
(52,612)
(53,369)
(43,528)
(55,640)
(45,799)
(46,892)
Avg. MGD (rr>3/d)
.414
.376
.395
.165
.279
.193
.092
.211
.244
.247
.223
.481
.534
.273
.488
.470
.371
.473
.402
.413
(1567)
(1423)
(1495)
( 625)
(1058)
( 731)
( 348)
( 799)
( 923)
( 747)
( 844)
(1820)
(2021)
(1033)
(1696)
(1779)
(1404)
(1790)
(1522)
(1545)
Total MG
8.0
9.8
8.9
3.0
14.3
10.5
11.2
12.7
17.0
34.4
18.6 '
12.0
10.1
10.6
11.1
8.4
10.1
5.9
7.1
10.4
Control
(m3)
(30,280)
(37.093)
(33,686)
(11,355)
(54,126)
(39,743)
(42,392)
(48,070)
(64,345)
(43,339)
(70,401)
(45,420)
(38,229)
(40,121)
(42,014)
(31,794)
(38,229)
(22,332)
(26,874)
(39,490)
System
Avg. MGD
.383
.407
.395
.609
.461
.349
.361
.424
.550
.459
.599
.428
.325
.355
.357
.280
.325
.190
.235
.344
(m3/d)
(1450)
(1540)
(1495)
(2305)
(1745)
(1321)
(1366)
(1604)
(2082)
(1737)
(2267)
(1620)
(1230)
(1344)
(1351)
(1060)
(1230)
( 719)
( 889)
(1301)
* September 10 - 30
•« July 26-30
Study Procedures
In order to maintain the highest degree of Validity of the results of this study, to ensure the usefulness of
the technology developed, and to maintain the integrity of the system, the study did not modify the normal opera-
tion and maintenance of the system. These tasks were accomplished by the St. Charles Utilities. All phases of the
project were coordinated through the operations group. In addition, approval for the project was obtained from the
Maryland State Clearinghouse through the Maryland Water Resources Administration, the Maryland State Depart-
ment of Health and Mental Hygiene and the Tri-County Council for Southern Maryland.
To achieve the tasks of the project, simultaneous studies were conducted. Figure 6 presents -a time graph
depicting the sequencing of the tasks.
12
-------
Baseline Data Collection
Operational Data On Control System
Alum Addition to Cell D
Nitrification Studies
Alum Addition to Cell A
Report Preparation
A SONDJ F MAMJ J ASOND JF MAM J J ASONDJ FMAMJ JASOND J FMAMJ
1975 1976 1977. 1978 1979
Figure 6. Schedule of project tasks.
Baseline Data
During the period from August 1975 to September 1978, data were collected on control Cells B, E, and F.
These data were used to establish long-term background data on a three-cell series lagoon system and to serve as a
basis for evaluating data from the test system. Data from the test-system were collected from August 1975 to
September 1976. These data served to establish baseline concentrations and efficiencies in Cells A, C, and D.
Phosphorus Study
Phosphorus removal studies were conducted from August 1976 to September 1978. The study was designed
to investigate phosphorus removal by the addition of alum to the influent of the first cell (an aerated cell in this
case) or to the influent of the third cell of the three-cell system. The results were evaluated on the basis of removal
efficiency, chemical-use efficiency, process dependability and process ability to meet a consistent phosphorus level.
Chemistry— .......
Phosphorus removal by alum addition is basically a chemical precipitation process. The reaction between
the aluminum ion (Al+++) and the phosphate ion (PO4=) to form the insoluble aluminum phosphate (A1PO4J is
shown in Equation 1. <
A1+++ +
A1PC-4J.
(D
The source of aluminum used in this study was a water solution of filter alum, Al2(SO4> • 14H2O(aq).
The precipitation process with this chemical is shown in Equation 2. The weight ratio of Al/P is 0.87 g Al/l.Og
P (18).
14HaO(aq) + 2PO4=(aq) -» 2A1PC-4 + 3SC«4=(aq) + 14H2O
(2)
When filter alum is used as the source of aluminum, the weight ratio of alum to phosphorus (AlumrP) is
9.6 kg (22.1 Ib) of alum per 1 kg (2.2 Ib) of phosphorus. If alum is expressed in terms of Al2C>3, the theoretical
13
-------
weight ratio of alum to phosphorus (Alum:P) is 1.64 kg (3.61 Ib) of Al2C>3 per 1 kg (2.2 Ib) of phosphorus.
Jar tests were used to determine the Al to P ratio required for a desired residual phosphorus content. These
jar tests were performed in accordance with the procedures outlined by the Allied Chemical Corporation (19).
Alum Specifications—
The filter alum used in this study was purchased from the Allied Chemical Corporation and shipped in
bulk lots of 15,000 Z (4,000 gal) by insulated tank truck. The specifications for liquid alum are shown in Table 3.
TABLE 3. COMPOSITION OF LIQUID ALUM
Weight % as Al
Weight %
Weight%asAl2(SO4)3 • 14H2O
Density at 16°C
4.37%
8.3%
49.0%
11.lib/gal
(1.33 g/2)
Chemical Storage and Handling Equipment—
The storage and handling facilities for the alum shown in Figure 7 were constructed at the study site be-
tween August 1975 and September 1076.
To Cell A
r- *• ToCettD
Heated
Alum
Storage
Tank
Q. Chemical Feed Pump
Raw Wastewater Piping
'— Chemical Feed Piping
Figure 7. Storage and handling facilities for alum.
An Owens-Corning Fiberglass, insulated tank with electric heater, Model 105M, was installed at the plant site. The
tank volume was 18.3 m3 (4,840 gal). An adjacent I building was constructed to house the chemicalfeed pumps.
14
-------
Two, BIF Industries Chem-O-Feeder Duplex Chemical Proportioning Diaphragm feed pumps, capacity 1.3 x 10 -
1.3 x 10~2 a/sec (0.125 - 12.5 gph), were installed and connected to the chemical storage tank. Calibration curves
were prepared to correlate pump stroke setting with chemical output. ABS plastic pipe, 1.90 cm (0.75 in) was used
to pipe the alum to the points of addition. This piping was buried in the lagoons to protect it against the cold weather.
The addition of alum to the influent of Cell D was done in the chemical contact chamber as shown in Figure 8. The
Motor
Baffle
Figure 8. Chemical contact chamber.
chamber was constructed by placing a steel crescent-shaped baffle 0.61 m (2.0 ft) in front of the influent pipe. The
Cell D influent and alum were mixed by a variable speed, U. S. Motors mixer Model 095464 mounted on the baffle.
A 1.93-m (6.3-ft) shaft and a propeller were connected to the motor. The propeller was located 0.43-m (1.4 ft) from
the influent pipe. The feed line was located such that the alum was added to the water surface at a point 0.61 m
(2 ft) directly above the propeller. A speed of 550 rpm was used to mix the wastewater and alum.
Alum was added to Cell A through a tap which was installed 61 m (200 ft) upstream from the end of the
influent pipe to Cell A. The force main acted as the chemical contact chamber. Chemical contact was effected by
the natural turbulence in the force main.
Chemical Addition Process— j
Chemical addition to Cell D, the effluent cell, began in September 1976 and continued through August
1977. Bench scale testing of alum, using jar tests, was performed in order to establish the optimum alum concentra-
tion to achieve a 1.0 mg/e total phosphorus concentration in the effluent. The results of these tests indicated that a
concentration of 32.3 mg/e. alum as Al2C>3 (18.1 mg/s as Al) should be used as the initial concentration for further
15
-------
testing on the field scale. The determination of the feed rate alum concentration was predicated on a determination
of the flow into Cell D. The only true measure of the flow through Cell D was the discharge rate at the pump station,
located in the cell. This rate varied as much as 300% on a daily basis as a result of normal operating procedures used
by the St. Charles Communities Utilities. Therefore, feed rate calculations were based on the more realistic values
obtained from averaging daily effluent flows.
The average flow rate, 1000 m3/day (0.270 MGD) indicated that the initial feed rate should be 220 me/min
in order to achieve the dosage. However, the extreme cold weather in November 1976 caused the effluent pump
station and flow meter to be severely damaged. It was therefore impossible to continue using this method at that
time. A feed rate of 160 m2/min was set based on the achievement of a target effluent concentration for total phos-
phorus of 1.0 mg/R and the fact that the system had reduced flow during the winter months. The pump station and
flow meter were repaired in June 1977 at which point? the feed rate remained at 160 me/min. This value produced a
76% removal of total phosphorus.
Chemical addition to Cell A, the influent cell, began in September 1977 and continued through September
1978. Jar tests were again performed to establish the optimum alum concentration to achieve a 1.0 mg/e total phos-
phorus concentration in the effluent of Cell A (Station 5). The results indicated that a 42.7-mg/e alum as A12O3
(22.6-mg/£ Al) should be used.
The chemical feed rate necessary to achieve this concentration was 330 me/min. This was determined by
using the average flow value 1220 m3/day (0.320 MGD) for the prior 12-month period ending in August 1977.
Since this feed rate would have caused an excessive use of alum, 164 me/min were used for the majority of
the period. This value gave a consistent (70%) removal of total phosphorus and also was within the theoretical
AliP ratio value of 1.0 to 1.6.
NITRIFICATION STUDY
The study of nitrification of the effluent of a three-cell lagoon started in September 1977 and continued
through September 1978. A plastic-media, trickling fitter pilot unit was used and operated throughout the study at
a recirculation rate of 1:1 and a hydraulic loading of 81.2 e/min/m^ (2
Biochemistry-
Nitrification is the two-step, sequential, biological oxidation of ammonia nitrogen, first to nitrites and then
nitrates. The two bacterial genera involved are Nitrosomonas and Nitrobacter.
Nitrosomonas oxidizes ammonia to nitrites according to the reaction shown in Equation 3. The stoichio-
metric oxygen requirement for nitrification as determined by Stankewich (20) is 4.57 mg C«2/mg NH4+ oxidized.
NH4+ + 1.5 O2 -4 NC-2" + 2H+ + H2O
(3)
Nitrobacter oxidizes nitrites to nitrates according to the reaction shown in Equation 4.
NO2" + O.'S O2 - NOs' , >(4)
The reaction carried out by Nitrosomonas produces an energy yield of 58-84 kcal per mole of ammonia oxidized (21).
' ' i t. •'
Oxidation reactions by Nitrobacter yield 15.4 - 20.9 kcal per mole of nitrate oxidized (21). From an
energy standpoint, the higher yielding reaction carried out by Nitrosomonas will produce more biomass (cells) than
Nitrobacter (21).
16
-------
Parameters Important to Nitrification Activity
The parameters which are important to the physiological and ecological components of nitrification and
are, therefore, engineering considerations of the process, include: temperature, ammonia, dissolved oxygen, pH,
alkalinity and BOD.
Temperature-
Over a given temperature range which an organism can tolerate, rate processes tend to increase proportion-
ately to increasing temperatures. Generally a 10°C rise in temperature increases a physiological rate by a factor of
2 or 3. This relationship is quite useful for estimating biological performance with respect to different temperatures.
When applied to the nitrification process, the estimated rate of NH4+ conversion may be estimated over a given
temperature range.
Ammonia—
The source from which organisms obtain their energy is an important factor in determining a given popula-
tion density. Since Nitrosomonas obtains energy through the oxidation of ammonia, its population density is thus
limited by the availability of ammonia. Nitrites produced by Nitrosomonas provide the energy source for Nitrobactor.
Nitrite concentration is therefore a principle factor determining the population dynamics of Nitrobactor.
Dissolved Oxygen—
The oxygen requirement for nitrification is 4.6 mg O2/mg NH4+ oxidized. This ratio is significant when
considering the high degree of nitrification that is desired in wastewater treatment systems. An additional oxygen
requirement will be imposed on the aquatic environment because of the oxidation of organic matter by heterotrophic
bacteria. Since the energy required for nitrifier growth is directly related to the presence of oxygen, it is important
that oxygen be provided at least in stoichiometric amounts.
pH and Alkalinity—
Low pH values have been shown to have an inhibitory effect on nitrification (25). During the nitrification
process, hydrogen ions are produced which destroy alkalinity at a ratio of 7.14 mg CaCOs/mg NH4+-N oxidized to
NO3"N. It is important that sufficient alkalinity be present to buffer the production of H+ and insure that the pro-
cess is not inhibited.
Different investigators have reported varying optimal pH ranges for nitrification (26). A pH range of 7.2 -
8.0 has been estimated as optimal for combined carbon oxidation-nitrification systems; however, this may be con-
servative when applied to separate state nitrification systems (27). It must be realized that where pH is concerned,
most bacteria have the capability to acclimate to changing environments, thus, different optimal pH ranges will be
observed.
BOD-
In conventional nitrification systems as well as attached growth nitrification systems, the coexistence of
heterotrophic and autotrophic bacteria (nitrifiers) is inherent. Because most systems have a limited surface area
upon which bacteria can grow, interspecific competition for this resource occurs. Heterotrophic bacteria oxidize .
organic material which yields a higher energy value than the nitrification process. This results in a faster growth rate
for heterotrophic bacteria. These ecological facts are significant, since the different growth rates of various species
will have ah effect on the overall species composition of the bacterial population.
BOD constitutes an estimate of the organic material available to heterotrophic bacteria, therefore it is
important that this value be relatively low to preclude the competitive exclusion of nitrifying bacteria. A concentra-
tion of BOD with regard to nitrogen, which restrains heterotrophic growth, will increase the competitive ability of
nitrifiers.
17
-------
Equipment
A vinyl core, B. F. Goodrich nitrification power was installed in November 1976. It was located at the
southwest corner of the lagoon system, adjacent to Cell F. (See Figure 9) This tower had a cross-sectional area of
CellC
ower
'' Recycle
CellB
CellE
A Booster Pump
D Influent Pump
A Recirculation Pump
.•-11; Tower Effluent
--— Force Feed Line
Figure 9. Tower location.
1.2 m2 (13 ft2), a media depth of 7.2 m (24 ft), and a media surface area of 99 m2/m3 (30 ft2/ft3), for a total
surface area of 830 m2 (9200 ft2). The design hydraulic loading was 20-120 B/min/m2 (0.5 - 3.0 gpm/ft2).
Process Description
The influent for the tower came from the pump station located in the southwest corner of Cell D and was
pumped continuously by one, 5.1-cm (2-in), Gprman-Rupp self-priming centrifugal pump. This pump force fed a
smaller, 3.8-cm (1.5-in) Gorman-Rupp pump at the base of the tower. The tower influent line was submerged in
Cell F in order to protect the line from freezing. To|wer recycling was provided by a 3.8-cm (1.5-in), Gorman-Rupp
pump at the tower base. Hydraulic flow was measured and controlled by adjusting the head of water flowing through
60° V-notch weirs which were located at the top of, the tower. Even distribution over the media was provided by a
belc-driven distributor located beneath the weir bojj:es. There were no facilities provided for the settling and con-
centration of sludge in either the recycle or effluent stream. Details of the tower piping are shown in Figure 10.
18
-------
Tower Overflow k
Feed Overflow
B. F. G. Vinyl Core Tower — 48' Diameter
33' - 41/2" O. A. H.., with 24' of B. F. G.
Vinyl Core Biological Oxidation Media
Force Feed Pump
Raw Feed Suction
Feed Pump
Recycle Pump
Figure 10. Tower piping.
The tower system was field tested to determine mechanical dependability at the site. The results of the
testing led to the establishment of the hydraulic loading of 6.8 x 10"5 2/s-cm2 (2 gpm/ft2) and the recirculation
ratio of 1:1, both of which were used during the nitrification study.
SAMPLE COLLECTION AND ANALYSIS
The sampling program was designed to monitor the common influent to the test and control systems, the
effluent of each of the three cells in the two systems, and the influent and effluent of the nitrification system.
19
-------
!•
s
I
ni
S
I
CL,
20
-------
The sampling stations used in this study are shown in Figure 11. Stations 2, 3, 5, and 6 were located within
the transfer vaults connecting the various cells of the lagoon system. Station.7 was located in the southwest corner
of Cell D, approximately 1.8 m (6 ft) from the bank between the two test systems' effluent pumps. Station 4 was
located in Cell F, approximately 1.8 m (6 ft) from the bank and 0.9 m (3 ft) from the south wall of the chlorine
contact chamber. Station 9 was located within the chlorine contact chamber and Station 8 at the tower discharge.
Station 1 was located in the wet well of the influent pumping station. The parameters, sample type, sampling location
and sampling frequency of the study are shown in Table 4.
TABLE 4. SAMPLING PROGRAM
Parameter
Fecal Coliform - count 100/mfi
pH - Units
DO - mg/2
Alkalinity - mg/2
Temperature - °C
Total BOD 5 - mg/2
Soluble BODs - mg/2
TKN - mg/B
NH3N-mg/2
NO2"/NO3" - mg/2
Total P - mg/2
Soluble P - mg/2
Total Suspended Solids - mg/e
Volatile Suspended Solids - mg/2
SO4= - mg/G
Algae Count & Identification
Cl2 Residual - mg/2
Sample
Type
G
C
G
C
C
C
C
C
C
C
C
C
C
C
C
G
G
Station
1# 2 3 4 5 6 7 8# 9
** ** ** **
* * * * * * * *
* * * *****
* * * * * * * *
* * * * ** * *
* * * * * * * *
** ** **, ** ** ** «* **
*** *****
* * * * * * * *
* * * * * * **
*** *****
* * * * *** * *
*** *****
* * * * * * * *
** ** ** ** ** ** ** **
** ** ** ** **' «*
**
* M, W, Th
** p
# All parameters from these stations were measured from grab samples
G Grab sample
C Composite sample
21
-------
Those samples designated as "composite" were obtained using a Brailsford and Company (Model EVS-1,
Series B) automatic effluent sampler, with a 2.3-B glass sample container (see Figure 12). These samplers collected
constant volume, at a constant time frequency to obtain a 2-fi (2.1-qt) sample in a 24-hour period.
• 30.5 cm
Pump
Vent
Battery}
Sample
Container
u
cq
o
LO
From Lagoon
Figure 12. Automatic effluent sampler.
The composite samplers at Stations 2, 3, 5| and 6 were housed in 210-K (55-gal) black steel drums. The
drum and sampler were positioned in the manhole of the transfer vault as shown in Figure 13.
22
-------
Drum
Composite
Sampler
F|OW!
Housfr
/
Suction
Line
Water Level
Flow
Figure 13. Transfer vault with sampler.
The flexible tygon® suction lines were housed in 1.8-cm (0.75 in), PVC pipe which allowed positioning of
the inlet line in a downstream orientation. Composite samples located at Station 4 and 7 were also housed in 210-e
(55-gal), black steel drums. These sampler drum units were positioned at the bank of the southwest corner of Cell D
and the bank of the west corner of Cell F, respectively. The suction lines were positioned with wooden arms to with-
draw samples 1.8 m (6 ft) from the lagoon banks as shown in Figure 14.
Suction Lines
Figure 14. Sampler drum unit.
23
-------
Grab samples at Stations 2, 3, 5, and 6 were taken from the influent side of the transfer vault. Grab samples
from Stations 4, 7, and 9 were collected 0.6 m (2 ft) from the lagoon embankment.
Dissolved oxygen and fecal coliform samples were obtained in separate 300-me BOD bottles. The samples
for algae analysis were obtained in 1-2 glass bottles.
The samples obtained at Station 1 were grab samples. They were taken from the wet well at this location at
a depth of 9.1 m (30 ft) using a 9.5-2 (2.5-gal) bucketand were then transferred to closed containers for transport.
I
All samples from Station 8 were grab samples! and were obtained by filling sample containers from the
effluent pipe.
The sampling program was modified to accommodate holidays, inclement weather and equipment mal-
functions. In those instances when less than three samples were taken during a week, the Monday sampling schedule
was followed to insure a minimum of one analysis per week on all parameters. Occasionally when the composite
samplers malfunctioned, a grab sample was obtained at the normal grab sample location. During extremely cold
periods, the lagoons became covered with ice and all sampling was discontinued until thawing occurred.
I
At the conclusion of each sampling period, all samples were transported to the laboratories at the College
and stored at 4°C until analyses were completed. (
ANALYTICAL PROCEDURES AND APPARATUS
All analyses were performed by professional personnel of the Pollution Abatement Technology Department
in the laboratories of the Charles County Community College. The laboratories utilized were: the Analytical Labora-
tory-used for all wet chemical analyses; the Microbiology Laboratory used for the fecal coliform analyses and algae
counts; and the Research Laboratory used for the Technicon Autoanalyzer I.
All analyses were performed in accordance with the procedures given in Standard Methods for the Analysis
of Water and Wastewater, 14th edition, 1975, or the EPA Manual of Methods for Chemical Analysis of Water and
\Yastes, 1974. The methods and the special laboratory [equipment used for the measurement of these parameters are
outlined in Table 5.
Meteorological Data
Precipitation and air temperature (maximum, average and minimum) were collected at a weather station
located in LaPlata, Maryland, 16 km (10 miles) from the lagoon site. The information was taken from Climatological
Data, NOAA, 1975 - 1978. These data are presented in Appendix C.
24
-------
H
2
W
>— (
D
Cf
• w
O
H
^
P^
O
M
5-
SPECIAL
Q
»-»•
TABLE 5. METHODS A*
#
*
§
^
•<:
I? CM
bo W
rt
w
'o *
H
*U r*")
W 4J
:flS g
T3
1
Is
rt
C/3
S
6
&,
'§•
w
Method
imeter/Units
S3
CM
'
r-3
o\
1
i
— o
S °
Fecal Colifori
Number per ]
T-I
'
O
^
o
1—1
•o
Fisher Me
pH Meter
Electrometric
52
1
ffi
o,
CS
T-H
10
(
1
Winkler (Azide Modification),
Fixed in the field
~s
go
Dissolved Oxj
mg/fi
i
oo
c5
o
13
T3
Fisher Mo
pH Meter
Potentiometric titration to pH 4.5
W Oi
ft
< 0
.
^*"
1
ro
S
T3
U
•^
w
3
s: S
— t 0
• 0
'•8 S S
Membrane electrode; samples filter
through 934A Reeve Angel glass fil
filters; then added directly to 300 i
BOD bottles
jy'
3
"3
52-
0^5;
O op
cq S
VS
!
0
10
Dichromate reflux; 20 me sample
«
OJO
c
<
O
b
Q
O
U
f^
I
o
•0
r
0
Sample filtered through 934A Ree\
Angel glass fiber filters; followed b]
dichromate reflux; 20 mfi sample
f,
g
COD (Soluble;
oo'
00
T-H
•a
CU
10
^
TH
!
i— i
Nl
Technicon
Autoanaly:
Digestion and distillation; followed
by automated phenate method
5!
•r
2f
(A
1
H
o\
N
00
1— )
1
1— (
53
to
Technicon
Autoanaly:
Automated phenate method •
Oi
I?
V}
CtJ
O
"8
25
-------
o
£-H
Phosphorus (
as P, mg/z
^
*•!
i
S
^
§
s
.
f»
Technicon
Autoanalyzer I
Filtration with 934A Reeve Ange
glass fiber filters; followed by
persulfate digestion and the auto-
mated Ascorbic Acid Reduction
^?
43
J3
"o
to
Phosphorus (
as P, mg/2
CO
1— I
1
1
•3-
'0\
,
Mettler Balance,
Model HIOT
Gooch crucible fitted with 934A
Reeve Angel glass fiber filters
i 1
', O
Suspended S
(Total)/mg/K
^
T-l
1
in
o\
Mettler Balance,
Model HIOT
u
o
O
V)
.2
a
en
So,
O en
Suspended S
(Volatile)/m;
^
r*
i
r
^O
o\
-------
DATA ANALYSIS
All data from the project were entered in an IBM 5100 portable computer. The monthly averages of the
chemical and microbiological analyses are presented in Appendix A, by station. The results shown in Appendix B
give the high, average and low values, as well as the standard deviation for each parameter at each station. The
geometric mean has been calculated for specific parameters and is also shown in the Appendices.
ALGAE ANALYSIS
The identification and enumeration of algae were conducted in an effort to establish the phytoplankton
dynamics of the lagoon system. Knowledge of algal populations, both quantitatively and qualitatively, is important
for several reasons: 1) Photosynthetic activity of algae provide a major portion of the oxygen necessary for aerobic
degradation of organic matter in facultative lagoons; 2) algae maintain an important link in the food chain of lagoon
ecosystems; 3) during certain periods, algae constitute a major portion of suspended organic solids and 4) algae play
an important role in maintaining certain amounts of nutrients in the lagoon system.
SAMPLE COLLECTION
Phytoplankton samples were collected at Stations 2 - 7 (see Figure 11). Sampling was initiated October 7,
1977 and continued on a weekly basis through September 29, 1978. One-liter grab samples were obtained 23 cm
(9 in) below the surface in 1300-mC glass bottles. The sample temperature was determined immediately and each
sample was tagged. Samples were preserved by adding 36 m& of merthiolate fixative to the sample bottles (22).
Each sample was stored at 4°C and concentrated by the sedimentation technique (23). Resulting concentrations
ranged from 10 - 25 mfi.
EXAMINATION
Phytoplankton samples were examined with a flat-field binocular microscope. A preliminary examination
was performed at 1000 X to precisely identify each form by genera. After each preliminary examination, enumera-
tion was performed at 400 X using a Palmer-Maloney counting cell and whipple eye-piece micrometer. Twenty fields
were examined from each sample. All counts were made as clump counts by which each naturally occurring single
filamentous, colonial or single cell organism was scored as one unit. The number of units/mfi was calculated given
the area of the counting cell, volume of original sample, the volume of sample concentrate, the number of fields
counted and the area of whipple grid (23). Clarification and identification were according to Prescott (24). A com-
plete listing of the algae identified by genera and estimated densities is provided in the discussion section.
27
-------
SECTION 6
RESULTS AND DISCUSSION
BACKGROUND DATA STUDY
The first task of the project was to gather | operational data over a 3-year period on a three-cell lagoon
system. Cells B, E, and F were referred to as the "control" cell systems. Monthly averages for all sampling stations
arc presented in the Appendices (A and B). Yearly and 3-year averages for each parameter of the control system are
presented in Table 6.
TABLE 6. CONTROL LAGOON SYSTEM YEARLY AVERAGES*
BOD COD
Alk Tot Sol Tot Sol
Phosphorus Suspended
TKN, NH3N NO^/NO^ Tot Sol Solids
Station 1
First Year
Second Year
Third Year
Three Yr. Avg.
180
192
202
192
160
177
118
149
77 307
89 396
60 352
73 349
163
211
159
174
17.8,
22.4!
27.4;
23.4;
13.3
20.7
26.6'
20.4
.28
.24
.27
.26
9.6
15.1
9.6
10.6
8.1
11.1
7.5
8.7
134
147
145
142
47
58
45
49
Station 2
First Year
Second Year
Third Year
Three Yr. Avg.
Station 3
First Year
Second Year
Third Year
Three Yr. Avg.
Station 4
First Year
Second Year
Third Year
Three Yr. Avg.
158
166
157
160
152
161
136
147
146
149
122
138
28
30
28
29
23
25
18
22
25
21
14
20
11
10
11
11
10
8
5
7
10
7
5
7
119
172
161
148
100
120
103
107
107
112
88
101
57
71
76
68
53
60
99
53
53
55
50
52
13.3;
13.8,
15.5;
14.4'
10.9
ll.s;
10.1
10.7
9.3
9.1
7.6
8.5
9.5
11.0
13.6
11.4
9.0
9.1
8.6
8.9
7.4
6.9
6.1
6.8
.22
.21
.77
.4
.39
.24
.50
.38
.42
.32
.47
.40
8.0
9.4
6.6
7.9
7.7
9.0
5.9
7.4
7.2
8.3
4.8
6.6
7.1
8.1
5.3
6.7
6.8
8.2
5.0
6.5
6.5
7.3
4.1
5.8
52
77
63
63
42
46
40
42
45
43
31
39
21
35
41
32
19
31
34
28
22
33
37
30
*Units of all parameters are in mg/2.
The control lagoon was studied to determine if a three-cell lagoon system could meet the secondary treat-
ment standards of 30-mg/fi BOD; suspended solids [as well as the 200 MPN/100 me standard for fecal coliform
28
-------
concentration in the effluent. Two-cell and one-cell systems were also examined. In addition, the effects of lagoon
treatment on nitrogen as measured by total Kjeldahl Nitrogen (TKN), ammonia nitrogen (NH3/N) and nitrite/nitrate
nitrogen (NO2"/NO,3") were examined. The natural reduction of total phosphorus and soluble phosphorus through
the system was also analyzed.
Biochemical Oxygen Demand (BOD)
The monthly averages for the overall lagoon influent and Stations 2, 3, and 4 (Cells B, E, F) effluent for
BOD are presented graphically in Figures 15, 16, and 17, respectively.
I I I I I I I I I I I I I I M I I I I I I I I I I I I I I I I I I I I I
30 mg/e BOD
standard
A = Raw Influent Station 1
O = Cell B Effluent Station 2
SNJMMJ SNJMMJ SNJMMJ S
1975 1976 1977
Figure 15. BOD, raw influent and Cell B effluent.
29
-------
Q
O
03
300
250
200
150
100
48:
44
40
36
32
28
24
20
16
12
8
4
I I I I | I I I I I I I I I I I |
I I i I I I
I I i I i I I
30 mg/C BOD Standard
= Raw Influent Station 1
i n ' ' ' ' i '
0= Cell E Effluent Station 3
' ' I i i i i I t i i i i i i i i i i I i i i i I i i
SNJMMJSfJjMMJSNJMMJS
1975 1976 1977 1978
Figure 16. BOD, raw influent and Cell E effluent.
300
Si
oi
Q
O
CO
= Raw Influent Station 1
O = Cell F Effluent Station 4
i i i I i i i i i i i i i i i I i i I i i i i I
SNJMMJSNJMMJSNJMMJ S
1975 1976 1977 1978
Figure 17. BOD, raw influent and Cell F effluent.
30 .
-------
The BOD standard of 30 mg/e was met 66% of the time for Cell B, 92% of the time for Cell E and 86%
of the time for Cell F. This is on a monthly basis for the entire period of study. On a yearly basis, BOD removal is
more consistent for Cells E and F.
A further evaluation of the control system, as shown in Figure 18, indicates that there is a 92% probability
that a three-cell system will meet the 30-mg/8 BOD standard. A two-cell system will meet the standard 92% of the
time, while a one-cell system will only meet the standard 63% of the time.
O)
Q
O
00
20 30 40 50 60 70 80
98 99 99.9
Percent Probability
Figure 18. Probability of BOD remaining in the control system.
It can be concluded from the data that a two-cell lagoon system whose first cell is aerated will meet existing
EPA effluent limitations for BOD. For the period during which this study was conducted, the percent removal BOD :
for the first cell was 81%, for the first two cells it was 86%, and for the overall control system it was 87%. On this
basis, there appears to be no justification for the third cell. In fact, the value of the second cell is questionable. The
soluble BOD concentration in the influent system was 49% of the total BOD over the period of the study. The sol-
uble BOD for the effluent of Cells B, E, and F was 37%, 33%, and 33%, respectively. From this it may be concluded
that the majority of soluble BOD is converted to insoluble BOD in the first cell of the system and that little conver-
sion of soluble BOD to insoluble BOD occurs in the second and third cells.
Suspended Solids
The raw influent and cell effluent suspended .solids monthly averages for Stations 2, 3, and 4 (Cells B, E,
and F) are presented graphically in Figures 19, 20, and 21, respectively.
31
-------
I I I I I I I I I I I I I I.I I I I I I I I I I I I I I I I I I I I I I I
A = Raw Influent Station 1
O = Cell B Effluent Station 2
210,-
^
en
160
CO
•a
01
1 110
60
30
10
I I I
I I i i i i i
v ,30 mg/£ Suspended Solids Standard
i i i i i I ' i I I I I I I I I I I
S N J M M J S
1975 1976
N J
J S N
1977
J M M J
1978
Figure 19. Suspended solids, raw influent and Cell B effluent.
210 -
I I I I | I I I I I I I I I I I | I I I I I I I I
Raw Influent Station 1
O = Cell E Effluent Station 3
30 mg/fi Suspended Solids Standard
i i i i i i
SN JMMJSNJMMJSNJMMJS
1975 1976 1977 1978
Figure 20. Suspended solids, raw influent and Cell E effluent.
32
-------
200
160
o
V)
•a 110
I
I
-------
160
V)
0.5 1 2
10 20 30 40 50 60 70 80 90
98 99
99.9
Percent Probability
Figure 22. Probability of suspended solids removal in the control system.
The 3-year average of percent volatile suspended solids in the influent was 81%. Cells B, E, and F had
3-year percent volatile solids averages of 86%, 87%, and 84%. Due to the nature of this system, the variation in
percent volatile solids can most likely be attributed to the algae populations which increase and decrease with sea-
sonal changes.
From this data, the suspended solids standard of 30 mg/2 was not met over the 3-year period by either a
single, two-cell, or three-cell lagoon system. The average removal efficiency between the second cell (Cell E) and the
third cell (Cell F) was only increased from 70% to 73%.;
In view of the BOD data previously presented, the third cell of this three-cell system has limited value in
reducing the second cell's effluent to secondary standards for BOD and suspended solids.
At the time this report was being prepared, the state of Maryland had raised the suspended solids standards
on lagoons to 90 mg/2 in the effluent (33). Considering this new standard, it can be shown that the effluent from a
two-cell system would meet the local state's suspended solids standard consistently. A one-cell aerated system would
still remain questionable.
Fecal Coliform
The fecal coliform values for the control and test systems are shown in Appendix D.
34
-------
The 3-year geometric mean of the fecal coliform count in the influent was 7.6 X 10° MPN/100 me. The
3-year average geometric mean of the fecal coliform count in the unchlorinated effluent of Cell F was 1.5 X 10?
MPN/100 mB. Only 15%,of the samples analyzed on the unchlorinated effluent of Cell F were below 200 MPN/100
me. The geometric mean of the fecal coliform count in the chlorinated effluent was 5 MPN/100 me. Chlorination of
Cell F effluent resulted in a log reduction in the influent of 6, compared to a log reduction of 3 for the unchlorinated
effluent.
It can be concluded that a reduction of fecal coliform organisms occurs in a three-cell lagoon system, a
level of 200 MPN/100 me for fecal coliform cannot be achieved without chlorination of the effluent.
Nitrogen.
40.0
35.0 -
30.0
la, 25.0
6
o
6
20.0
15.0
10.0
5.0
I I I I | I I 1 I I I III I I . | I I 1
O O Station 1
•- -• Station 2
Station 3
Station 4
I i
SNJMMJSNJMMJSNJMMJS
1975 ' 1976 1977 1978
Figure 23. Ammonia of raw influent and effluent for Cells B, E, and F (Stations 1, 2, 3, and 4).
Figure 23 graphically presents 3-year data on the ammonia concentrations of the raw influent and the
effluent for Cells B, E, and F (sample Stations 1, 2, 3, arid 4, respectively).
Cell B had a 3-year ammonia average reduction of 44%. Cells E and F had a 3-year average reduction of
22% and 24%, respectively. The higher reduction occurring in the first cell (Cell B) can be attributed to the aeration
of that cell, and the larger amounts of nitrogen available for utilization by bacteria. '
35
-------
The two-cell system (Cells B and E) had an overall 3-year removal efficiency of 56%, while the complete
three-cell system had an overall removal efficiency of i67% for the 3-year period. The trend forTKN concentration
shows a similar pattern. •
D)
z
ks
O
1.0
0.8
0.6
0.4
0.2
Station 1
Station 2
Station 3
Station 4
S N J
1975
M M J S
1976
N; J M M J S
1977
N J
M M J
1978
Figure 24. Nitrate/nitrite of raw influent and effluent of Cells B, E, and F.
The nitrite/nitrate nitrogen (NO2~/NO3~) data for Cells B, E, and F is presented in Figure 24. The majority
of NC>2~/NO3" formation occurs in Cell B and then decreased in Cells E and F. Again, this behavior can be attributed
to the aeration of Cell B.
From the nitrogen data presented, the effluent ammonia is much lower during the summer months, indi-
cating greater microbial action during this time. The winter months have higher values indicating a reduced biological
activity.
The aeration of Cell B has the greatest impact on reducing the ammonia concentration, while increasing
the NO2"/NC>3~ concentrations. Furthermore, Cells E 'and F have no effect on increasing the NC^'/NOj" concentra-
tion, although they provide an approximate 40% reduction in ammonia.
36
-------
Phosphorus
O)
o
"I
o
0.
I
15.0
12.0
9.0
6.0
3.0
I I I I | I M II I I I I I I | I I I I I I I I I | I [ I I I I I I I I
Station 1
_ _„ Station 2
g g Station 3
C, ,& Station 4
' ' ' I I I I I I I I i I i I i I i i i i i I i i i i i I i i i i i i i i
SNJMMJSNJM
1975 1976
/IJSMJMM.J S
1977 1978
Figure 25. Total phosphorus concentrations of raw influent and effluent of Cells B, E, and F.
The total phosphorus concentration for the test system atStations 1, 2, 3, and 4 is presented in Figure 25.
Utilizing average concentrations for three years, it can be seen that the phosphorus concentration was
reduced by 25%, 6%, and 11% for Cells B, E, and F, respectively. The two-cell system of B and E had a reduction of
30%, while the three-cell system had an overall reduction of 38%.
37
-------
15.0
?12.0
x-
t 9-0
to
O
£
CD
3 6.0
3
3.0
I I I I I I I I I I I i I I I I I I
I I I I I I I I I I i I I i I I i
Station 1
Station 2
Station 3
Station 4
i i i i t I i i i i i i i i I t i i i i i i i i i i i I I I I i i I I I I.
S N
1975
J M M
1976
J S N
J Ml M
1977
J S N
J M M
1978
J S
Figure 26. Soluble .phosphorus of raw influent and effluent of Cells B, E, and F.
The soluble phosphorus data for the 3-year study period is presented in Figure 26. Cells B, E, and F (Sta-
tions 2, 3, and 4) had phosphorus reductions of 22%, 3%, and 11%, respectively, over the 3-year period. The first
two cells had a. 3-year average reduction of 24%, while the three-cell lagoon system had an average reduction of 33%.
These reduction rates are lower than the total phosphorus reductions. Soluble phosphorus accounts for 81% of the
total phosphorus in the influent. After passing through Cell B, the soluble becomes 84% of the total phosphorus.
It becomes 87% of the total phosphorus in Cell E and remains constant at 87% after Cell F.
PHOSPHORUS STUDY
Test System and Control System Comparability
In order to determine the effectiveness of ihe phosphorus removal process by the addition of alum in situ,
the experimental method required that the results from the test system be compared to the sister control system
operating in parallel. The assumption was that the control system would reflect the baseline operation of the test
system and thus, the effect of alum addition on phosphorus concentrations could be differentiated from normally
occurring variations in the phosphorus concentration!
The similarity of the test system, Cells A, C, and D, and the control system, Cells B, E, and F, was tested
during the first year of the project, September 1976 to September 1977, and the data was analyzed on two bases:
1) removal efficiencies across sister cells within the two systems (A - B, C - E, and D - F), and across the entire
system, and 2) water quality at sister sampling points in the two systems (2 and 5, 6 and 3, and 7 and 4) as shown
in Figure 27.
38
-------
Figure 27. Test and control systems.
The two-cell system of A - C and B - E operated with comparable efficiency as shown in Table 7.
TABLE 7. SYSTEM A - C AND B - E COMPARISON (% EFFICIENCY)
BOD
Tot Sol
COD
Tot Sol
NH3N
Phosphorus
Tot Sol
Suspended
Solids
System B - E
System A - C
86
85
87
87
67
68
69
70
32
44
20 16
21 12
69
69
The efficiency of Cell D was less than Cell F as shown in Table 8.
TABLE 8. CONTROL SYSTEM AND TEST SYSTEM (% EFFICIENCY)
BOD
Control
Test
Tot
84
74
Sol
88
82
COD
Tot
65
50
Sol
68
62
NH3.
44
38
Phosphorus
Tot
25
24
Sol
20
24
Suspended
Solids
67
46
The water quality at sister sampling points 5 - 2, 6 - 3, and 7 - 4, was measured in terms of total BOD,
total COD, suspended solids, total phosphorus, and soluble phosphorus. The data from the sister sites were com-
pared statistically using a t-test to establish the degree of similarity. The statistical analysis showed that there was no
difference in the water quality at Stations 5 and 2, and 6 and 3. However, the water quality at Stations 7 and 4 was
significantly different. The water quality at Station 7 was significantly poorer than at Station 4. This result, coupled
with the lower efficiency in Cell D, indicated possible abnormal conditions in Cell D.
The lagoon site was inspected for possible causes of the low performance of Cell D. A valve on a force
39
-------
main which fed Cell D was found to be leaking raw wastewater into Cell D. The valve could not be repaired without
major construction. In May 1978 the force main with ;the defective valve was plugged.
As a result of the comparability studies, the:data from the chemical addition studies during the second and
third years of the project will be evaluated differently. The effects of chemical addition to Cell D during the second
year will be evaluated by comparison of second-year1 data to the baseline data from the test system obtained during
the first year of the project. The effects of chemical addition to Cell A during the third year will be evaluated in two
ways, 1) by examination of data obtained from the test system during all three years of the project, and 2) by
comparison to third-year data from the control systenj for sister Cells B and E.
Second Year Chemical Addition
The yearly and 3-year averages for each parameter of the test system are presented in Table 9.
TABLE 9. TEST LAGOON SYSTEM YEARLY AVERAGES*
Year/
Station No.
~
Station 1
First Year
Second Year
Third Year
Three Yr. Avg.
Station 5
First Year
Second Year
Third Year
Three Yr. Avg.
Stiition 6
First Year
Second Year
Third Year
Three Yr. Avg.
Station 7
First Year
Second Year
Third Year
Three Yr. Avg.
BOD COD
Alk
180
192
202
192
169
159
131
152
154
142
116
137
138
86
117
116
Tot
160
177
118
149
31
27
28
29
24
24
19
22
41
31
26
33
Sol Tot
77 307
89 396
60 352
73 349
12 128
9 137
8 158
9 142
10 97
7 114
.5 111
7 106
14 152
12 104
9 136
11 178
Sol
163
211
159
174
58
67
64
62
49
56
53
52
61
56
68
62
TKM
17.8
27.4
27.4
23.4
12.0
12.5
16.4
14.0
9$
10.5
9.3
9^8
12.5
15.5
9.4
12.1
NH3N
13.3
20.7
26.6
20.4
10.1
9.8
13.6
11.3
7.5
8.2
7.7
7.8
8.2
13.9
8.1
9.7
0.28
0.24
0.27
0.26
0.27
0.30
0.39
0.30
0.49
0.24
0.57
0.43
0.16
0.16
0.75
0.36
Phosphorus
)3~ Tot
9.6
13.1
9.6
10.6
8.2
8.3
3.8
6.6
7.6
7.2
3.6
6.1
7.3
2.5
4.1
4.8
Sol
8.1
11.0
7.5
8.7
7.3
7.1
1.9
5.3
7.1
6.3
2.8
5.3
6.1
1.6
3.2
3.8
Suspended
Solids
134
147
145
141
54
51
75
61
41
41
45
42
72
32
41
53
SO4=
46
58
44
48
19
42
86
49
18
54
77
47
35
142
67
75
* Units of all parameters are in mg/8.
During the second year, the raw influent yras a slightly stronger waste than the first year as measured by
BOD, COD, NH3N, 804= and suspended solids parameters. During chemical addition to Cell D, Cells A and C oper-
ating efficiencies were similar to their efficiencies during the first year. The water quality produced by Cells A and C
was not significantly different from the water quality produced by sister Cells B and E during the same time period,
which can be seen by reviewing Tables 7 and 8.
40
-------
During periods of low or zero effluent discharge rates, alum which was being added to Cell D at the C - D
transfer vault would leak back to Cell C. This was caused by the fact that there was no significant hydraulic head
loss between the two lagoon cells to prevent water movement from Cell D to Cell C.
BOD and Suspended Solids
For the year prior to chemical addition in Cell D, the BOD concentration at Station 7 averaged 41 mg/fi.
The average BOD concentration during chemical addition was 31 mg/2 representing a 25% reduction over the pre-
vious year.
The BOD and suspended solids values are presented graphically in Figure 28. The baseline suspended solids
concentration in the effluent of Cell D (Station 7) was 72 mg/fi. The average suspended solids concentration during
chemical addition was 32 mg/2, representing a 55% reduction. The increased BOD values can be attributed to the
defective valve and in fact, extrapolation of six months of data during the third year shows that the BOD standard
of 30 mg/fi would have been met.
Data shows that the suspended solids standard of 30 mg/2 would not be met, but the 90-mg/fi standard
would be met consistently. Similar behavior was shown to exist in the control system.
I I I
I I I I
I I I I i I
i i i i i i—r
100
-Si
O)
o
to
"8
T3
C
0)
Q.
(/>
CO
~a
c
en
Q
O
00
80
60
40
20
•-• BOD
—O| Suspended Solids
1 ' ' ' I ' ' ' ' ' ' ' ' - f ' I ' ' ' '
'
S N
1975
J S
"1976
N J M
M J S
1977
J M M J S
1978
Figure 28. BOD and suspended solids of Cell D (Station 7).
41
-------
Nitrogen
Figure 29 represents the ammonia concentration for the test system.
o
I I I I | I I I I I I I I I I I | I I I I I I I I I I I | I I I I I I I I
Station 1
Station 7
40
30
20
10
I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I
SNJMMJSNJMMJSNJ.MMJS
1975 1976 i 1977 1978
Figure 29. Ammonia of raw influent and effluent of Cell D.
The ammonia concentration increased in the effluent of Cell D during chemical addition. For the year prior
to alum addition, the average ammonia concentration in the effluent was 8.2 nig/2. During alum addition, this value
increased to 13.9 mg/fi. There are several possible causes for this increase:
1. The increased organic matter caused by the addition of alum resulting in an increase in
anaerobic decomposition; and
2. The acidic condition present in the cell during alum addition causing a higher NH4+ concen-
tration.
Phosphorus
Figures 30 and 31 represent the total phosphorus and soluble phosphorus concentrations, respectively, for
the test system (Cell D).
42
-------
I
V3
3
O
O.
tn
O
Q-
'~ta
.«-
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
I I i I I i i i i i iii i I i i i i i
SNJMMJSNJMMJSNJMMJS
1975 1976 1977 1978
Figure 30. Total phosphorus of raw influent and effluent of Cell D.
16.0
14.0
.§ 12.0
«/>
D
1 10.0
• a..
o
f. 8.0
= • 6.0
o
CO
4.0
2.0
^ ' ' I '
f—Alum Addition
FT
I I I I I I 1 r
> Station 1
Station 7
SNJ-MMJS
1975 1976
NJMMJS
1977
NJMMJS
1978
Figure 31. Soluble phosphorus of raw influent and effluent of Cell D.
43
-------
Total phosphorus concentration in Cell D's effluent decreased 66% from the previous year's concentra-
tion. The average total phosphorus concentration in the effluent of Cell D was 2.5 mg/2 during alum addition and
7.3 mg/2 for the year prior to alum addition. During addition of alum to Cell D, there was an 81% reduction of total *
phosphorus in the raw influent, compared to a reduction of 24% for the previous year. The soluble phosphorus
concentration was reduced 74% from the previous year. During alum addition, the soluble phosphorus concentra-
tion averaged 1.6 mg/2 compared to a 6.1-mg/2 concentration prior to alum addition. The overall, phosphorus re-
duction of the test system was 85% during the period of alum addition to Cell D, compared to 25% the previous year
without chemical addition.
The addition of alum to Cell D resulted in a Jdecrease of BOD, suspended solids, total and soluble phospho-
rous. A significant increase in Nl^N suggests the absence of algae because a substantial amount of ammonia is
removed from the water and utilized as a nutrient source in the presence of these organisms. Although the percent
reduction in soluble phosphorus unproved from 25 to 85%, it was not possible to maintain less than l-mg/2 soluble
phosphorus. Total phosphorus could not be maintained at 1 mg/2 or less, even though its reduction increased from
24% to 81%. ;
Alum was fed continuously into Cell D at the transfer pipe from Cell C. Because the lagoon did not discharge
continuously, it became apparent that during long periods of no discharge for Cell D, the alum solution seeped
through the transfer pipe into Cell C. This was noticed during the last few months of addition to Cell D. A slight
head loss from Cell C to Cell D would have prevented this and contained the alum solution in Cell D for more
contact with the water in Cell D. When evaluating the chemical addition to a lagoon, the system must be studied
so that proper containment of the applied chemical will occur. The defective valve in Cell D caused negative head
loss across the cell during periods of no discharge from the test system.
It can be concluded that the BOD standard [would be met when alum is added to the third cell of a three-
cell system. However, the secondary standard of 30-mg/fi suspended solids could not be met consistently.,
44
-------
Third Year Chemical Addition
The yearly and 3-year averages for BOD, COD, TKN, NH3, NO2~/NQ3-, suspended solids, total and solu-
able phosphorus are presented in Table 10.
TABLE 10. TEST LAGOON SYSTEM YEARLY AVERAGES*
Year/
Station No
Station 1
First Year
Second Year
Third Year
Three Yr. Avg.
Station 5
First Year
Second Year
Third Year
Three Yr. Avg.
Station 6
First Year
Second Year
Third Year
Three Yr. Avg.
Station 7
First Year
Second Year
Third Year
Three Yr. Avg.
BOD
Tot Sol
160
177
118
149
31
27
28
29
24
24
19
22
41
31
26
33
77
89
60
73
12
9
8
9
10
7
5
7
14
12
9
11
COD
Tot Sol
307
396
352
349
128
137
158
142
97
114
111
106
152
104
136
178
163
211
159
174
58
67
64
62
49
56
53
52
61
56
68
62
TKN
17.8
27.4
27.4
23.4
12.0
12.5
16.4
14.0
9.9
10.5
9.3
9.8
12.5
15.5
9.4
12.1
NH3N
13.3
20.7
26.6
20.4
10.1
9.8
13.6
11.3
7.5
8.2
7.7
7.8
8.2
13.9
8.1
9.7
NO2~/NO3-
0.28
0.24
0.27
0.26
0.27
0.30
0.39
0.30
0.49
0.24
0.57
0.43
0.16
0.16
0.75
0.36
Phosphorus
Tot Sol
9.6
13.1
9.6
10.6
8.2
8.3
3.8
6.6
7.6
7.2
3.6
6.1
7.3
2.5
4.1
4.8
8.1
11.0
7.5
8.7
1
7.3
7.1
1.9
5.3
7.1
6.3
2.8
5.3
6.1
1.6
3.2
3.8
Suspended
Solids
134
147
145
141
54
51
75
61
41
41
45
42
72
32
41
53
* Units of all parameters are in mg/2.
BOD and Suspended Solids (
During the third year of the study, alum addition was moved to Cell A from Cell D. The method utilized
for the addition of alum to Cell A is discussed on page 16. The BOD concentration at Station 5 averaged 28 mg/a
during the third year. This represents a 76% reduction in the BOD during this time. The first and second years'
BOD removals were 85% and 80% respectively. This indicated a leveling effect, possibly accelerated by the use of
alum. The,second cell of the test system (Cell C) had a BOD concentration of 19 mg/e in the effluent measured at
Station 6, as compared to 24 mg/E for the first and second years, indicating an increase in efficiency during the
third year.
f
Sister Cells B and E of the control system had total BOD concentrations of 28 and 18 mg/fi, respectively.
There appeared to be no increase in BOD removal in Cells A and C while alum was added to Cell A.
The third and final cell also had a lower BOD effluent concentration during the third year. Possible residual
effects of alum addition to Cell D the previous year could have influenced the cell's performance. This cause would
have been minor if present at all. In September 1977, when chemical addition terminated to Cell D, the BOD"
immediately responded with an increase. Any residual chemical effects would have delayed or prevented this in-
crease. The addition of alum to Cell A would require approximately 54 days to begin to effect the performance of
45
-------
Cell D. After the immediate increase in BOD concentration which occurred when alum addition was terminated
to Cell D, the BOD concentration begins to drop and continues to drop until April of 1978. This indicates that
the effect of adding alum to Cell A was beginning to appear in Cell D. When the defective valve in Cell D was re-
paired in May of 1978, the BOD concentration seems to stabilize laround 20 mg/£. It can be concluded therefore,
that the chemical addition in Cell A had an effect in reducing the BOD concentration of the test system.
During alum addition to Cell A, soluble BOD removal increased in Cells A and C. Efficiency in Cell C
increased during the second year, while the efficiency in sister Cell E, decreased. The soluble removal rate during the
third year was higher than die baseline year, but not as high as the second year when alum was fed to the final cell.
The control system showed no increase in soluble BOD removal during the third year.
The suspended solids concentration in the first cell, Station 5, and second cell, Station 6, increased during
the period of alum addition. Cells A and C of the test lagoon system removed 48% and 69% of the applied sus-
pended solids, respectively, compared to 56% and 72% for sister Cells B and E. Final effluent suspended solids con-
centration for the test system' was lower during the chemical addition to Cell A than for the baseline year. The
lowest yearly average of suspended solids concentration for the test system occurred during chemical addition to
Cell D in the second year. Comparison of the chemical addition in BOD and suspended solids data for the second
and third years shows that alum addition to the aerated first cell of a three-cell system is not as efficient in removing
BOD and suspended solids as alum addition to the third cell.
The BOD and suspended solids values are presented graphically in Figure 32. .,
100
80
I
V)
•o
C
n>
O
O
CQ
60
40
20
| | | I | I I I I I I I I I 1:1 | I I I I I I I I I I I | I I ' I I I I I
•- -• BOD
Suspended Solids
V
A
i i i i I i i ' ' i ' ' ' '
ill
i i i i i i i i
SNJMMJSNJMMJSNJMMJS
1975 1976 1977 1978
Figure 32. BOD and suspended solids - Cell A (Station 5).
46
-------
Chemical Oxygen Demand ,
Cell A had a total COD reduction of 55% during the third year, compared to reductions of 38% and 65%
for the first and second years, respectively. The two-cell system of A and C had a lower removal rate the third year
in comparison to the two previous years even though Cell C was more efficient the third year than the first and
second years. The three-cell system had higher total COD the third and first years, while experiencing a reduction
the second year when alum was being applied directly to the final cell. During alum addition to Cell A, the control
test system had a significantly higher COD removal rate.
The soluble COD parameter paralleled the characteristics of the total COD concentration. The efficiency
of Cell C during the third year was higher than the two previous years.
Chemical addition to the final cell of the three-cell system during the second year, produced a lower soluble
COD concentration in the effluent than chemical addition to the first cell of the system during the third year.
Nitrogen . '
iFigure 33 represents the ammonia concentration for the test system at Stations 1 and 5.
| I I I I I I I I
•Si
I?
40
30
20'
10 -
• • Station 1
Station 5
I I [ I I I I I I I I I I I | I I I I I I I I I
I i I I I I i i i i i i i i i i
i i i
i .....
i i i i i
S N
1975
M
M J S
1976
N
M M
J S
1977
N
M
M J
1978
Figure 33. Ammonia of raw influent and effluent of Cell A.
The ammonia concentrations increased in the effluent of Cell A during chemical addition. During the two
years prior to alum addition, the average ammonia at Station 5 was 9.8 mg/e. During alum addition, this value
increased to 13.6 mg/2. Since ammonia remained constant during the first two years, the increased concentration is
attributed to increased organic matter and acidic conditions as were shown in exist in Cell D.
Sulfate
During the year of alum addition to Cell A, sulfates increased 93% in Cell A, to a concentration of 86 mg/2.
This increase in sulfate concentration was reduced 22% by Cells C and D to a final effluent concentration of 67
mg/2. The baseline effluent concentration was 35 mg/fi. During the second year, while alum addition to Cell D was
being conducted, the final effluent concentration was 142 mg/2. This increase in sulfate levels in the final effluent
during the second and third years is to be expected with the addition of alum.
47
-------
During the year of alum addition to Cell A, the sulfate characteristics of the control system did not change
significantly. The control lagoon system experienced a 17% reduction in the sulfate concentration during the third
year with a final effluent concentration of 37 mg/2. The effects of the increased sulfate concentration in the ef-
fluent applied to land for final disposal was not examined in this study.
Total Phosphorus
Figure 34 represents the total phosphorus concentration for Cell A of the test system.
O—o Station 1
Station 5
S N J
1975
M M J S
1976
JSNJMMJS
1977 1978
Figure 34. Total phosphorus of raw influent and effluent of Cell A.
The total phosphorus concentration in Cell A effluent was 3.8 mg/8 during the third year. This compares
to 8.2 and 8.3 mg/B for the first and second years, respectively. During the first and second years, Cell A had a
27% reduction in total phosphorus, while it had a 60% removal rate during chemical addition in the third year.
Cell C had a 5% reduction during the third year,; contrasting a 10% reduction during the first and second years.
Phosphorus removal increased, in the first1 cell but not in the two following cells. Little additional phosr
phorus removal occurs in Cell C and the concentration actually increases in Cell D. During the third year, the
effluent of Cell D had a 14% increase in phosphorus over its influent, even though the baseline year showed a natural
4% decrease occurring in Cell D.
The data for the baseline year shows that the three-cell test lagoon system had averaged a 25% reduction
in total phosphorus concentration. The data from the second year in which chemical addition to Cell D occurred,
shows that the three-cell system had averaged an 81% reduction in phosphorus. Alum addition to Cell A during the
third year caused a 60% reduction in phosphorus. The control lagoon system had a 25%, 37%, and 50% reduction
in phosphorus for the first, second, and third years respectively. The effluent concentration at Station 7 during the
third year was 4.1 mg/fi, compared to 4.8-mg/e phosphorus concentration in the control system effluent and 2.5-
mg/fi phosphorus in the test system when alum was added to Cell D during the second year.
The Al/P ratios and dosage rates for Cell A are sh&wn in Table 11.
48
-------
TABLE 11. Al/R RATIOS AND DOSAGE RATES FOR CELL A
Date
9/77
10/77
11/77
12/77
1/78
2/78
3/78 (a)
3/78 (b)
4/78
5/78
6/78
7/78
8/78
9/78
Avg. Flow
MGD
0.193
0.092
0.211
0.244
0.223
0.481
0.534
0.534
0.273
0.488
0.470
0.371
0.473
0.402
Feed Rate
m2/min
160
160
160
160
160
88
88
164
164
164
164
164
164
164
|A1 Dosage Rate
mg/e
18.5
38.8
17.0
14.6
16.0
4.3
3.7
6.8
13.4
7.5
7.8
9.9
7.7
9.1
P Reduction
%
20
56
59
54
35
42
30
50
72
71
70
70
72
72
Al/P
1.9/1
3.4/1
1.9/1
2.0/1
2.4/1
0.5/1
0.4/1
0.8/1
1.5/1
1.1/1
1.0/1
1.4/1
1.0/1
1.0/1
Figure 35 compares the total phosphorus concentration in the effluent of Cell A and the calculated Al to
P ratio (Al/P) over a one-year period.
9.0
8.0
c*
•& 7.0
o
-C
Q.
v>
O
EX.
6.0
6.0
j§ 4.0
£
3.0
2.0
1.0
T
T
T
Total phosphorus
Al/P Ratio
_L
_L
_L
J_
O N
1977
D
M A
M J
1978
3.5
3.0
2.5
2.0
1.5
1.0
.5
0
o
v>
CO
Figure 35. Total phosphorus versus Al/P ratio in Cell A.
49
-------
This figure shows that from September 1977 to January 1978, the average Al/P was 2.3 to 1, with an average
effluent phosphorus concentration of 5.1-mg/2. During April 1978 to September 1978, the Al/P was 1.1 to 1, with
an effluent phosphorus concentration of 2.6 mg/2. During February and March of 1978, the chemical feed rate was
reduced to provide an Al to P ratio of approximately 0.5 to 1 which caused the phosphorus concentration in the
effluent to increase. At no time was a 1-mg/fi total phosphorus concentration achieved during the third year, either
in the final effluent or in the effluent of Cell A. The lowest phosphorus concentration reached was 2.5 mg/e in the
effluent of Cell A and 2.3 mg/2 in the three-cell test system.
Soluble Phosphorus
Figure 36 represents the soluble phosphorus concentration for Cell A of the test system.
I I I I I I I I I I I I I I I I I I I I I I I I
SNJMMJSiNJMMJ SNJMMJS
1975 1976 1977 1978
Figure 36. Soluble phosphorus of raw influent and effluent of Cell A.
The soluble phosphorus concentration in Cell A was reduced 10% of the first year (baseline) concentration; 35% the
second year and 75% the third year when alum was added to the influent of Cell A. This compares to a reduction of
12%, 26%, and 29% for Cell B, the sister cell of Cell A, during the first, second and third years respectively.
During chemical addition to Cell D in the jsecond year, Cell D experienced the same 75% reduction in solu-
ble phosphorus concentration that occurred when alum was added to Cell A. However, chemical addition to Cell A
produced a concentration of 3.2-mg/£ soluble phosphorus in the final effluent and chemical addition to Cell D pro-
duced a concentration of 1.6 mg/2 in the effluent. It can therefore be concluded that alum addition to Cell A did
cause a reduction in total and soluble phosphorus concentrations in the final effluent but not as significant a reduc-
tion as the addition of alum to Cell D. '
50
-------
Nitrification Study
The third task of the project was to evaluate a plastic media trickling filter nitrification tower on the basis
of efficiency and process dependability. The data pertaining to tower operation are presented in Appendices A and
B. The monthly averages for the parameters at Stations 7 and 8 are presented in Table 12.
TABLE 12. TOWER .INFLUENT AND EFFLUENT DATA
Year/Month
1977.
September
October
November
December
1978
January
March
April
May
June
July
August
September
Average
>H
6.7
6.9
6.7
6.3
7.2
7.2
7.4
7.4
7.0
7.7
7.7
Temp
°C
18.9
10.8
11.3
3.9
7.0
12.0
16.2
24.7
26.5
27.2
21.3
16.2
St
TKN
rng/8
9.1
10.6
13.6
16.1
12.6
11.4
6.4
4.1
4.2
4.2
5.1
8.9
ition 7
NH3
mg/E
6.7
8.7
11.8
14.6
11.4.
9.8
5.3
2.9
3.1
3.1
4.0
7.5
NO2VN03-
mg/B
0.12
0.18
0.14
0.14
0.14
0.17
0.41
0.83
1.07
2.45
3.09
0.79
D.O.
mg/e
2.5
!.£'
1.9
0.4
3.5
6.9
14.8
14.9
13.1
11.6
10.1
7.4
Alk
mg/8 '
120
152
139
136
127
120
98
108
98
89
95
116
Station 8
pH
7.4
6.9
6.4
6.0
Temp
°C
20.5
12.9
12.6
5.1
TKN
mg/B
9.7
8.0
8.3
12.5
NH3
mg/S
7.2
5.7
6.5
10.4
NO2VNb3
mg/8
0.91
4.06
5.60
3.52
D.O.
mg/e
7.3
7.4
8.8
10.4
Alk
mg/8
141
128
106
113
%NH3
Conv.
3
34
45
29
7.3
7.2
7.2
7.3
7.0
8.1
7.9
8.0
12.6
18.7
24.7
27.1
27.7
23.0
17.5
13.3
6.8
2.4
1.5
1.5
1.2
1.9
6.1
11.8
5.2
1.1
0.4
0.5
0.4
0.9
4.6
0.72
4.62
4.64
3.88
4.63
6.11
6.57
4.28
9.5
8.5
8.6
9.9
9.8
8.8
9.3
8.9
125
109
56
87
77
70
75
99
4'
47
79
86
84
88
78
39
* % Increase
Tower shutdown due to cold weather
Data collection on the nitrification tower was initiated on September 26, 1977 when the tower was started
after a 30-day shut down period. A 5-day period was required to establish nitrifying activity with the existing
influent characteristics. Initiation of nitrification was indicated through chemical analysis and by extensive foaming
in the cone at the tower bottom and tower discharge.
Conditions during the first 6 months of nitrification studies were represented by low temperatures and de-
creasing biological activity, with a corresponding rise in ammonia. Other factors such as D.O. and pH were also
below optimal levels based on previous studies (25). The pH ranged from 6.3-6.9, while D.O. ranged from 0.4-2.5
mg/fi. These factors as mentioned previously, are critical to the nitrification process and may have influenced
nitrification and NH3 reduction efficiencies during the period September 1977-December 1977.
Maximum efficiencies for the September 1977-December 1977 period were attained in November- (see
Table 12), during which time the NH3 conversion was 45%. Data recorded for September 1977 showed a net in-
crease in NH3 across the tower due to sloughing off of dead organic material from the tower media. This is also
indicated by the net increase in suspended solids and BOD as shown .in Table 13. .
51
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TABLE 13. TOWER INFLUENT AND EFFLUENT RELATIONSHIPS FOR
BOD AND SUSPENDED SOLIDS
Year/
Month
1977
September
October
November
December
1978
January
February
March
April
May
June
July
August
September
Average
Station
Total BOD
(mg/e)
29
40
35
41
—
—
22
20
22
17
26
18
19
26
7 j
Total Suspended Solids
(mg/2).
92
69
72
46
i
—
—
50
57
74
41
55
28
35
56
Station
Total BOD
(mg/e)
36
38
37
33
—
—
23
17
22
19
20
18
15
25
8
Total Suspended Solids
(mg/2)
142
82
55
30
—
45
48
58
54
46
29
27
56
— Data not available. [
September 1977
November 1977
March 1978
April 1978
January 1978
Averages for stations includes last two days of month
Includes suspended solids data for 10 and 11
Includes all suspended solids data for Stations 7 and 8
Includes all
BOD data for Stations 7 and 8
All Station 7 data omitted
During January 1978, severe freezing temperatures necessitated the shut down of the tower. On February
24,1978, startup was initiated; however, due to much colder temperatures, 34 days were required to achieve nitri-
fication activity. Nitrogen increases across the tower recorded in March 1978 indicated that dead organic material
was being sloughed off the media following tower restart in February 1978. This is shown by the net increase in
BOD in Table 13.
Consistent nitrification was achieved from May 1978 through September 1978, averaging 83%. Table 14
shows no significant differe'nce between the tower influent and effluent organic nitrogen during the 12-month study.
52
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TABLE 14. TOWER INFLUENT AND EFFLUENT RELATIONSHIPS FOR
ORGANIC NITROGEN
Year/Month
1977
September
October
November
December
1978
January
February
March
April
May
June
July
August
September
Average
Station 7
Org N (mg/fi)
1.7
1.9
1.8
1.5
—
—
1.2
1.6
1.1
1.2
1.1
1.0
1.1
1.4
Station 8
Org N (mg/e)
2.5
2.3
1.8
2.1
—
—
1.5
1.6
1.3
1.1
1.0
0.8
1.0
1.5 '.
— Data not available.
Nitrification activity for the month of April 1978 is representative of a period during which increased
nitrifier activity was occurring. This is indicated in Table 12 by nitrification values intermediate to those recorded
during March and May 1978. During the March-May period, tower influent pH, D.O. and temperature increased to
values which are more optimal to the nitrification process (25). These parameters changed as a result of moderating
environmental conditions and elimination of an influent leak in Cell D. The combined effect of the changes in
influent quality and ambient temperatures is reflected by increases in nitrification efficiency from 4% in March
1978, to 79% in May 1978. Irrespective of the reason for the changes in tower influent, the results show that in-
fluent chemical quality and ambient temperature effect tower operation efficiency.
Influent consisted of high BOD, low pH and low temperatures When low levels of nitrification were observed
from September to December 1977. Consistent high rate nitrification 080% NH3 conversion) was maintained during
the wanner months (May 1978 - September 1978). In view of the results obtained during the 12-month sampling
period, process dependability for nitrification seems to be strongly related to favorable environmental conditions.
Nitrification studies conducted in the past have shown the nitrifying process to be relatively low in solids
yield (25). The data collected in this study would seem to substantiate these previous findings. Although the final
effluent exceeded the secondary standard of 30-mg/B suspended solids, this can be .attributed to higher influent
suspended solids concentrations. Average results for the 12-month sampling period show no significant difference
between influent and effluent suspended solids, except for periods following initial startup and sloughing.
effluent.
BOD data listed in Table 13 and Figure 37 show no significant difference between tower influent and
53
-------
45
40
35
S? 30
O>
— 25
Q
2 20
15
10
5
•—• Station 7
O—O Station 8
I I I
I I I I I I I I
S N J M M J S
1977 1978
Figure 37. BOD tower influent and effluent.
As stated earlier, hydrogen ions produced during the nitrification process destroy alkalinity at a ratio of
7.14 mg CaCC>3/1.0 mg NH3 oxidized to NO2" (37). From data listed in Table 12 for months during which nitri-
fication occurred, an average ratio of 6.9 mg CaCO3/1.0 mg NH3 was obtained. This is in general agreement with
the above theoretical value.
Microbiological Correlation
Total algae counts for the test and control systems are provided in Table 15 and depicted in Figures 38
and 39 respectively. Figures 38 and 39 indicate that both systems follow similar annual patterns with respect to
total phytoplankton concentrations. The control i system shows a gradual increase in algal density from October
1977 through March 1978 (Figure 39). A similar trend is shown in Figure 38; however, the algae population appears
to be less stable than that of the control system. Both the test and control systems show a sharp decline in the algae
population during May 1978. This decline was most probably due to grazing activities of zooplankton such as
Rotifers and Dapbnia which were present in large numbers during May. Following the low densities in May, algae
populations in both systems showed a rapid recovery reaching a peak in July 1978. This is followed by a gradual
decrease in both systems, most probably the result of declining water temperatures.
54
-------
TABLE 15. TOTAL ALGAE-COUNTS X 103/me
Control System
Cell B Cell E
1977
October 18 12
November 39 38
December 38 57
1978
January 18 37
February 33 81
March 65 75
April 43 30
May 10 4.5
June 31 42
July 33 161
August 25 65
September 19 , 55
Average 31 55
1 1 1
- 5"^
I ,>\
§ V
— ' . CT
o
O)
O o «•
1
3
, ^J f\
f
<
1 -
I 1 1
ON D
1977
Test System
CellF Cell A CellC Cell D
6.4 13 24 42
34 22 43 111
90 5.2 75 4.3
72 8.9 14 6.8
119 46 127 133
149 95 46 44
27 117 40 66
3.8 8.4 8.8 14
32 16 20 47
265 39 272 349
61 21 61 198
16 23 31 72
73 35 63 91
| 1 1 I 1 1 1 1 1
J£NX/V
v
¥
• Cell A
A Cell D
O CellC _
1 i 1 1 i i I 1 i
J MAMJJAS
1978
Figure 38. Total algae counts for the test system.
55
-------
CX
E
c
,3
O
• = Cell B
A = Cell F
O = Cell E
I
I
I
I
J_
I
O N D
1977
M
A M J
1978
A S
Figure 39. Total algae cojunts for the control system.
Euglenophyta
The Division Euglenophyta was represented by two species of Euglena. Examination of Figures 40 and 41
show a regular decline in the density of Euglena, beginning in November and ending in February 1978, with com-
plete disappearance in both systems. This suggests;that in addition to other parameters, water temperature is a pri-
mary factor in controlling the density of Euglena. '
56
-------
CO
i 2
O)
UJ
• = Cell B
A = Cell E
O = Cell F
_L
_L
1 L
O N D
1977
M
1978
Figure 40. Density of Euglena in the control system.
I •
J. 3
o
CD
C
_aj
en
LU
i—r
T
i—r
j i i
OND
1977
= Cell A
= Cell D
O = Cell C
J J L
M
MJ
1978
Figure 41. Density of Euglena in the test system.
57
-------
While it is not readily apparent in Figures 40 and 41, examination of Table 16 indicated the population of
Evglena to be more dense in the influent (Cells A and B), with a gradual decrease in the following cells in the control
system. Apparently Euglena is more competitive in the influent cells due to a higher tolerance to the more polluted
water. The population density in Cell D however, shows an increase over that of Cell C in the test system.
TABLE 16. EUGLENA COUNTS X 103/me
Year/
Month
1977
October
November
December
1978
January
February
March
April
May
June
July
August
September
Average
CellB
13
9.3
0.11
0.06
-0-
0.54
3.2
67
18
13
16
15
8.1
Control System
CellE
8.6
8.7
0.34
0.04
-0-
0.32
6.9
3.1
6.8
6.3
11
1.5
4.5
CellF
1.7
5,2
0.27
I
0,11
-jo-
0.03
2.5 •.
0.94
2.8
44
2.2
0.21
1.5
Cell A
9.0
11
0.18
-0-
-0-
0.09
2.8
4.7
9.5
28
8.4
14
7.4
Test System-
Cell C
.2.5
3.9
0.07
0.07
-0-
0.52
9.7
5.4
3.9
5.8
4.0
5.6
3.4
CellD
4.7
2.6
0.06
-0-
-0-
0.50
11
5.6
6.1
5.2
3.9
7.9
4.0
Cbloropbyta (Green motile algae)
Green motile algae in the Division Chlorophyta were represented by Pandorma, Eudonna and three species
of Cblamydomonas. Volvox was observed occasionally during preliminary examinations; however, it was never
observed during enumeration procedures.
Figures 42 and 43 graphically depict the population dynamics of the green motile forms identified in the
lagoon system. These algae were always present in both systems, except during December 1977 when none were
observed in Cell A of the test system. Eudonna and Pandorina were the less abundant forms appearing only sporad-
ically throughout the 12-month sampling period. The three species of Chlamydomonas (designated in this study as
CblamydomonasiC2 and Cy) by far were the more abundant forms, and have had the greatest impact on the slopes
of the curves in Figures 42 and 43.
58
-------
E 4
S 3
e>
I I II
ill ii ii
• = Cell A
A = Cell D
O = Cell C
j I
ONDJFMAMJJAS
1977 1978
Figure 42. Population dynamics of green motile forms in the test system.
• = Cell B
A = Cell F
O =Cell E
O N D J F
Figure 43. Population dynamics of green motile forms in the control system.
59
-------
Except for the December 1977 period in Cell A and the May 1978 period in both systems, the gradual increase and
decrease in the population density represents ecological replacement of one species of Cblamydomonas by another.
During October 1977, Cblamydomonasi was the more abundant species, but was gradually replaced by Chldmydo-
mona$2 in November 1977. ChlamydomonaS2 was clearly the dominant species in December,with Chlamydomonasj
being observed in only one sample. From January 1978 through the middle of May 1978, Chlamydomonas3 .gradu-
ally increased in density over Cblamydomonas2 to be more abundant than Chlamydomonasj and also during this
period, Cblamydomonas± reappeared in both systems. From June 1978 through August 1978, Chlamydomonas3
disappeared and Cblamydomonas2 remained dominant over Chlamydomonas^. The period August 1978 through
September 1978 showed Chlamydomonas^ to increase in density over that of Cblamydomonas2-
Examination of Table 17 indicated the concentration of Chlamydomonas to be less dense in the influent
cells and the density in the last two cells in each series not being significantly different.
TABLE 17. MOTILE GREEN ALGAE COUNTS X 103/me
Year/
Month
1977
October
November
December
1978
January
February
March
April
May
June
July
August
September
Average
CellB
4.0
27
26
as
33
64
27
0.57
0.72
11
7.2
2.8
18
Control System
CellE
1.7
27
54
3.2
80
67
2.9
0.38
23
95
42
42
36
CellF
1.0
27
89
65
117
123
0.60
1.0
1.5
6.0
8.5
11
37
i
Cell A
7.0
10
-0-
0.52
46
92 '
112
1.0
1.5
11
3.7
7.5
24
Test System
Cell C
7.7
36
71
10
127
45
2.3
1.4
6.3
40
16
22
32
Cell D
25
12
22
5.1
132
43
4.6
7.9
2.6
30
48
38
31
Cbloropbyta (Green nonmotile algae)
The nonmotile green algae represented the- most diverse group encountered with respect to total numbers
of genera identified. Table 18 lists the different genera observed during the 12-month sampling period. These in-
clude all genera classified in the Division Chlorophyta, except the motile forms placed in the Order Volvocales.
60
-------
TABLE 18. PHYTOPLANKTON GENERA IDENTIFIED
Division
Genus
Euglenophyta*
Chlorophyta
Cyanophyta
Euglena
Cblamydomonas
Pandorina
Tetraedron.
A nkisstro desmus
Actinastrum
Closteridium
Trochiscia
Phytoconis
Chlorella
Oocystis
Colenkina
Scenedesmus
Chloroscarcina
Closterium
Arthrospira
Oscillatoria
Spimlina
Trichodesmium
Agmenellum
Anabaena
Raphidiopsis
Unidentified
* Classification according to Prescott (24)
Figures 44 and 45 show the population densities of this group for the test and control systems respectively.
It is evident that the influent cells of both systems maintain a less stable population of nonmotile green algae when
compared to the last two cells in series. This is indicated by "0" population densities during October 1977, and
February and August 1978 for the test system arid February 1978 for the control system.
61
-------
ON D JFMAM J J AS
Figure 44. Population densities of nonmotile green algae for the test system.
ON'DJ FMAM J J AS
1977 1978
Figure 45. Population densities of nonmotile green algae for the control system.
62
-------
Figure 46. Densities of blue-green algae in the control system.
1 1 1 T
ONDJ FMAMJ JAS
1977 1978
Figure 47. Densities of blue-green algae in the test system.
63
-------
Table 19 clearly shows that this group is more abundant for both systems in the last two cells in each series
than in the two influent cells. | ?
TABLE 19. NONMQTILE GREEN ALGAE COUNTS X 103/me
Year/
Month
1977
October
November
December
1978
January
February
March
April
May
June
July
August
September
Average
CellB
0.20
1.6
1.9
2.5
-0-
0.57
12
2.3
5.3
0.22
0.18
0.04
2.2
Control System
CellE
1.3
1.7
2.5
0.46
-0-
6.8
20
1.0
12
59
9.3
9.7
10
CellF
2.7
jl.7
JL.3
0.85
J0.19
2?
24
M
28
255
50
5.2
33
Cell A
-0-
0.02
3.8
8.3
-0-
2.7
2.5
2.0
1.1
0.18
-0-
0.02
1.7
Test System
CellC
102
5.1
3.2
1.3
0,09
0.44
28
0.33
9.0
225
40
3.2
27
Cell D
12
•95
3.1
1.6
0.19
0.18
50
0.89
14
313
146
26
55
Cyanopbyta
The blue-green algae were the least abundant forms observed in the lagoon system. Seven different genera
were identified as indicated hi Table 18 under the Division Cyanophyta. Raphidiopsis was the most abundant
form present and occurred regularly throughout the 12-month sampling period. All other blue-greens appeared
sporadically. Figures 46 and 47 show the population densitites for the test and control systems, respectively. The
wide fluctuations in densities in both systems are a result of short and temporary increases in a given genus.
64
-------
Table 20 shows that blue-greens tend to be more dense in the influent cells of both systems and decrease
in density with the following cells in each series.
TABLE 20. BLUE-GREEN ALGAE COUNTS X 103/mfi
Year/
Month
1977
October
November
December •
1978
January
February
March
April
May :
June
July
August
September
Average .
CellB
0.93
1.0
9.5
0.67
-0-
0.09
0.02
0.41
7.8
8.2
1.3
1.3
2.6
Control System
CellE
0.32
0.32
0.48
4.5
0.23
0.12
-0-
-0-
0.24
0.10
2.3
1.5
0.85
CellF
0.08
0.03
0.04
6.2
1.3
0.19
-0-
-0-
0.02
-0-
-0-
-0-
0.66
Cell A
0.71
0.39
0.14
0.11
-0-
0.06
-0-
0.65
4.1
0.10
0.75
1.3
0.70
Test System
Cell C
0.27
0.23
0.25
2.3
0.28
0.06
-0-
0.11
0.87
0.34
0.52
0.59
0.49
Cell D
0.11
0.38
4.7
0.05
0.86
0.12
0.12
0.14
0.53
-0-
0.35
0.45
0.65
The algae genera identified in the St. Charles lagoon system are typical of those inhabiting a polluted
environment (26). Relative densities follow an annual cyclic pattern as a result of environmental and biological
influences, With maximum peak densities occurring in July. The diverse planktonic populations characteristic of the
final cells in series indicate that the lagoon system is operating below maximum loading. However, it is hypothe-
sized that the high densities during the warmer months contribute significantly to the organic suspended matter in
.the final effluent. .
65
-------
Economic Considerations
The cost for nutrient removal is normally expressed as cost per 1,000 gal. Alum addition to Cell D produced
an effluent with an average total phosphorus concentration of 2.5 mg/e, while alum addition to ("ell A produced an
effluent with 4.1 mg/fi average total phosphorus concentration. This represents removal rates of 81% arid 60%,
respectively.
The costs to maintain these rates, using liquid alum, is estimated to be 9.6 cents/1,000 gal for addition to
the third cell and 6.1 cents/1,000 gal for addition to the first cell. The higher removal rates which occurred in
Cell D produced an average cost of $2.60/ Ib P removed. This compares to an average cost of $3.04/lb P removed
during alum addition to Cell A. Based on present costs, percent removal rates, and the natural reduction of phosphorus
in the first cell, it would be more economical to utilize in-cell alum addition to the third cell in order to obtain a
desired 1.0 mg/C total phosphorus concentration in ;the effluent.
Nitrification of the effluent of Cell D produced a consistent ammonia reduction of 83% after the tower had
equilibrated. Since the facility that was studied used a side stream to test, the projected operating costs were not
determined. These costs would include rental fees, as compared to a facility using a tower to nitrify the entire
effluent, in which case the purchase price would be needed. The values may also vary depending on the size of the
lagoon and the type of operation employed.
Since the tower operation is dependent on the climatic conditions at the installation site, consideration
should be given to site specific environmental conditions, such as temperature, when considering the operating and
maintenance costs. '
66
-------
SECTION 7
SUMMARY
The major benefit of this project has been the generation of reliable and sufficient data to assess accurately
the feasibility and project the cost of (a) removing phosphorus from lagoon effluents utilizing in-cell alum addition,
and (b) nitrifying lagoon effluent by passage through a plastic-media, attached-growth biological system. These
methods of; controlling phosphorus and nitrogen compounds in lagoon effluents were selected for long-term evalua-
tion from a vast number of possible processes that involve more complex unit operations producing a larger volume
of solids to be treated.
It was found that both in-cell alum addition and tertiary plastic-media nitrification are compatible with
lagoon operation and will not destroy the basic simplicity and relative ease of operation that has made lagoons at-
tractive to small communities. The results should be of interest to design engineers and regulatory personnel holding
the responsibility for approving permits for lagoon effluent discharges.
It is hoped that these data, as well as the conclusions and recommendations from this project, will have a
significant impact on new and upgraded lagoon designs that not only must incorporate nutrient control, but also
effect improved overall treatment.
67
-------
REFERENCES
1. Federal Water Pollution Control Act, As Amended (33, U. S. C. 466 et seq.), 1977.
i
2. Maryland Water Resources Administration Newsletter, JERA-Repatts^ "Suspended Solids Limits for Muni-
cipal Discharge Permits," Fall 1978.
3. Porges, R., and K. M. Mackenthun, Waste Stabilization Ponds: Use, Function, and Bioata, Biotechnology and.
Bioengineering. 5(4) :25 5-273. 1963.
4. Barsom, G., Lagoon Performance and the State of Lagoon Technology. EPA Technical Service Report
R2-73-144, Washington, DC, 1973.
5. Champlin, R. L., Supplementary Aeration of Lagoons in Rigorous Climate Areas. EPA Water Pollution Con-
trol Research Series, October, 1971. • ' '
6. Christiansen, C. D., Coarse Bubble Diffusers for Aerated Lagoons in Cold Climates. EPA Artie Environ-
mental Research Laboratory, College, AK, Working Paper No. 17, January, 1973.
i ' - ' "'
7. Upgrading Wastewater Stabilization Ponds to Meet New Discharge Standards. Proceedings of a Symposium
held at Utah State University, Logan, UT, PRWG159-1, August 21-23, 1974.
8. Reynolds, J. H., R. E. Swiss, C. A. Macko, bid E. J. Middlebrooks, Performance Evaluation of an Existing
Seven Cell Lagoon System. EPA-600/2-77-086, August, 1977.
9. Bowcn, S. P., Performance Evaluation of Existing Lagoons, Peterborough, New Hampshire. EPA-600/2-77-
085, August, 1977.
10. McKinney, R. E., Performance Evaluation, of an Existing Lagoon System at Eudora, Kansas. EPA-600/
2-77-167, September, 1977.
11. Shindala, A., and J. W. Stewart, Chemical Coagulation of Effluents from Municipal Waste Stabilization
Ponds. Water and Sewage Works. 118(4):100-103,1971.
12. Shindala, A., Nutrients and Algal Removal from Oxidation Pond Effluents. Presented at the Sixth Mississippi
Water Resources Conference, Mississippi State University, Water Resources Research Institute, State College,
1971. ',
13. Graham, J. J. and R. B. Hunsinger, Phosphorus Reduction from Continuous Overflow Lagoons by Addition
of Coagulants to Influent Sewage. Catalog No. En43-ll/65, Minister of Supply and Services, Canada, 1977.
14. Boyko, B. I. and J. W. G. Pupke, Aerated Lagoons in Ontario: Design and Performance Considerations. Pro-
ceedings from International Symposium on Waste Treatment Lagoons, Ross E. McKinney (editor). Spon-
sored by the Missouri Basin Engineering Health Council, Kansas City, MO and the U. S. Department of the
Interior, Federal Water Quality Administration, Washington, DC, 1970.
68
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15. Duddles, G. A. and S. E. Richardson, Application of Plastic Media Trickling Filters for Biological Nitrifica-
tion Systems. EPA-R2-73-199, June, 1973.
16.
17.
18.
19.
20.
21.
Stone, R. W., D. S. Parker, and J. A. Cotteral, Upgrading Lagoon Effluent for Best Practicable Treatment.
J. Water Pollution Control Federation, Vol. 47, No. 8, August, 1975.
Bdrchardt, J. A., S. J. Kang, and T. H. Chung, Nitrification of Secondary Municipal Waste Effluents by
Rotating Bio-Discs. EPA-600/2-78-061, June, 1978.
Process Design Manual for Phosphorus Removal, U. S. Environmental Protection Agency, Technology
Transfer, April, 1976.
Allied Chemical Corporation, Industrial Chemicals Division, Valley Forge Executive Mall, 676 Swedesford
Road, Wayne, PA 19087.
Stankewich, M. J., Biological Nitrification with the High Purity Oxygenation Process. Presented at the 27th
Annual Purdue Industrial Waste Conference, Lafayette, IN, May, 1972.
Process Design Manual for Nitrogen Control, U. S. Environmental Protection Agency, Technology Transfer,
October, 1975.
22.
23.
24.
Weber, C. I., The Preservation of Phytoplankton Grab Samples. Transactions of the American Microscope
Society, Vol. 87, 1968.
Standard Methods for the Examination of Water and Wastewater. 14th ed., APHA, AWWA, WPCF, 1975.
Prescott, G. W., How to Know the Freshwater Algae. 2nd ed., William C. Brown Company, Dubuque, IA,
1970. ,
25. Mulbarger, M. C., The Three Sludge System for Nitrogen and Phosphorus Removal. Presented at the 44th
Annual Conference of the Water Pollution Control Federation, San Francisco, CA, October, 1971.
26. Palmer, C. M., Algae and Water Pollution. EPA-600/9-77-036, December, 1977.
69
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TECHNICAL REPORT DATA
(Please redd Instructions on the reverse before completing)
.REPORT NO.
EPA-600/2-80-155
3. RECIPIENT'S ACCESSION-NO.
I. TITLE AND SUBTITLE
FIELD STUDY OF NUTRIENT CONTROL IN A MULTICELL
LAGOON
5. REPORT DATE
August 1980 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHORtS) _ ,
William T. Engel
Thomas T. Schwing
8. PERFORMING ORGANIZATION REPORT
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Charles County (MD) Community College
P.O. Box 910
LaPlata, Maryland 20646
10. PROGRAM ELEMENT NO.
PE #35B1C, Task D-l/28, SOS #3
11. CONTRACT/GRANT NO.
R-803636
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory-Cm., OH
Office of Research and Development
U.S. Environmental Protection Agency >
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
13. TY.PEQF REPORT,
Final //75-
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES i
Project Officer: Edward J. Opatken (513) 684-7643
^.ABSTRACT Thfs report covers nutrient control in a serially arranged, multicell
aerated lagoon system over a three yean period. The objective was to develop reliable
technology for reducing phosphorus and for converting ammonia-nitrogen to nitrate-
nitrogen.
A six-cell lagoon was modified into two independent three-cell systems-. One
system was maintained as a control and the other was the test system used for-nutrient
control. Alum was added to the .third cell of the test system. Another test was
conducted with alum being fed to the first cell. The alum addition in: the third
cell was more effective in reducing phosphorus.
A plastic media tower was added afjter the third cell in the test system for
nitrification of ammonia-nitrogen* Consistent nitrification was achieved during
the warmer months and reduced efficiencies were obtained during the cold weather
months.
17.
KEY WORDS AND DOCUMENT-ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Wastewater
Lagoons
Phosphorus Removal
Nitrification
Alum Addition
Nitrification plastic
media packed tower
Ammonia conversion
1.3B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport}
Unclassified
21. NO. OF PAGES
82
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
70
•ft- U.'S. GOVERNMENT PRINTING OFFICE: 1980--657-165/0123
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