WATER POLLUTION CONTROL RESEARCH SERIES
ISOSOELYS/T-I-S
REC-R2-7I-6
DWR NO. 174-9
BIO-ENGINEERING ASPECTS OF AGRICULTURAL DRAINAGE
SAN JOAQUIN VALLEY, CALI PORN I A
REMOVAL OF NITROGEN
FROM TILE DRAINAGE
A SUMMARY REPORT
MAY 1971
ENVIRONMENTAL PROTECTION AGENCY0RESEARCH AND MONITORING
CALIFORNIA DEPARTMENT OF WATER RESOURCES
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BIO-ENGINEERING ASPECTS OF AGRICULTURAL DRAINAGE
SAN JOAQUIN VALLEY, CALIFORNIA
The Bio-Engineering Aspects of Agricultural Drainage
reports describe the results of a unique interagency study
of the occurrence of nitrogen and nitrogen removal treat-
ment of subsurface agricultural wastewaters of the San
Joaquin Valley, California.
The three principal agencies involved in the study are
the Water Quality Office of the Environmental Protection
Agency, the United States Bureau of Reclamation, and the
California Department of Water Resources.
Inquiries pertaining to the Bio-Engineering Aspects of
Agricultural Drainage reports should be directed to the
author agency, but may be directed to any one of the three
principal agencies.
THE REPORTS
It is planned that a series of twelve reports will be
issued describing the results of the interagency study.
There will be a summary report covering all phases of
the study.
A group of four reports will be prepared on the phase of
the study related to predictions of subsurface agricul-
tural wastewater quality — one report by each of the
three agencies, and a summary of the three reports.
Another group of four reports will be prepared on the
treatment methods studied and on the biostimulatory
testing of the treatment plant effluent. There will be
three basic reports and a summary of the three reports.
This report, "TECHNIQUES TO REMOVE NITROGEN IN DRAINAGE
EFFLUENT DURING TRANSPORT", is one of a group of three
reports which also include (2) possibility of reducing
nitrogen in drainage water by on farm practices, and
(3) desalination of subsurface agricultural wastewaters.
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BIO-ENGINEERING ASPECTS OF AGRICULTURAL DRAINAGE
SAN JOAQUIN VALLEY, CALIFORNIA
REMOVAL OF NITROGEN
FROM TILE DRAINAGE
A SUMMARY REPORT
Based on Reports
Prepared by the
California Department of Water Resources
William R. Gianelli, Director
Environmental Protection Agency
Robert S. Ken Water Research Center
William C. Galegar, Director
Environmental Protection Agency
Region IX
Paul DeFalco, Director
The agricultural drainage study was conducted under the direction of:
Robert J. Pafford, Jr., Regional Director, Region 2
UNITED STATES BUREAU OF RECLAMATION
2800 Cottage Way, Sacramento, California 95825
Paul De Falco, Jr., Regional Director, Region IX
WATER QUALITY OFFICE, ENVIRONMENTAL PROTECTION AGENCY
760 Market Street, San Francisco, California 94102
John R. Teerink, Deputy Director
CALIFORNIA DEPARTMENT OF WATER RESOURCES
1416 Ninth Street, Sacramento, California 95814
DWR-WQO Grant #13030 ELY
DWR-USBR Contract #14-06-200-3389A
May 1971
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price 50 cents
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REVIEW NOTICE
This summary report has been
reviewed by the California Depart-
ment of Water Resources, the Water
Quality Office,, Environmental Pro-
tection Agency, and the U. S. Bureau
of Reclamation, and has been approved
for publication.
The mention of trade names or com-
mercial products does not constitute
endorsement or recommendation for use
by either of the two federal agencies
or the Department of Water Resources.
11
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ABSTRACT
Studies conducted by members of an interagency
group have shown that it is technically feasible to remove
nitrate from subsurface agricultural tile drainage by either
of two biological processes, algae stripping or bacterial
denitrification. Laboratory studies using process effluents
and untreated drainage demonstrated that nitrogen removal
effectively reduced the algae growth potential of the drainage
when mixed with waters from the Sacramento-San Joaquin Delta,
a possible discharge location for subsurface tile drainage
from California's San Joaquin Valley.
Algae stripping is an assimilatory nitrogen removal
process in which growth of algae in shallow outdoor ponds was
encouraged by the addition of iron, phosphorus, and carbon
dioxide.
The detention times required to meet the nitrogen
removal objective of the project, that is, to reduce an
influent of 20 mg N/l (milligrams nitrogen per liter) to
2 mg N/l, range from about 5 days in the summer to 16 days
in the winter. The algal suspension from the growth unit was
then harvested by coagulation-sedimentation, dewatered to about
20 percent solids by vacuum filtration, and air dried to about
90 percent solids. Possible markets for the algal product
include feeding as a protein supplement and use as a soil
conditioner.
Bacterial denitrification, mainly a dissimilatory
process in which most of the nitrate is reduced to nitrogen
gas, requires anaerobic conditions and an organic carbon source
such as methanol. The denitrification process was studied by
means of deep ponds and upflow filters. Results of the deep
pond studies indicate that ponds had to be covered to ensure
anaerobic conditions. When water temperatures were above
l4°C, detention times extending from 8 to 20 days were needed
to reduce nitrogen to the 2 mg N/l level. Below l4°C, the
effluent total N was about 3-5 mg/1 at detention times as
long as 50 days. The anaerobic filters produced an effluent
that contained 2 mg/1 or less total nitrogen, when operated
above l4°C with 1- to 2-hour detention time and using 1-inch
rounded aggregate. Below l4°C, a detention time of 2 hours
was required. Long-term operation of the filters indicated
that periodic flushing may be required to control bacterial
biomass within the filter.
Preliminary estimates for the two processes indi-
cated that treatment cost about $90 per million gallons
(about $30 per acre-foot) for the anaerobic systems and
$135 per million gallons ($45.per acre-foot) for algae
stripping. These figures will be refined using data from
the 1970 operational studies.
iii
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Two desalination processes, reverse osmosis and
electrodialysis, were also studied. The reverse osmosis
unit produced high quality effluent but relatively low
product flow. The membrane stacks also deteriorated. The
electrodialysis unit reduced total dissolved solids by
about 25 percent after one pass and a product flow of about
75 percent of the influent.
IV
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BACKGROUND
This report is one of a series which presents the
findings of intensive interagency investigations of practi-
cal means to control the nitrate concentration in subsur-
face agricultural wastewater prior to its discharge into
other water. The primary participants in the program are
the Water Quality Office of the Environmental Protection
Agency, the U. S. Bureau of Reclamation, and the California
Department of Water Resources,, but several other agencies
also are cooperating in the program. These three agencies
initiated the program because they are responsible for pro-
viding a system for disposing of subsurface agricultural
wastewater from the San Joaquin Valley of California and
protecting water quality in California's water bodies.
Other agencies cooperated in the program by providing
particular knowledge pertaining to specific parts of the
overall task.
The ultimate need to provide subsurface drainage
for large areas of agricultural land in the western and
southern San Joaquin Valley has been recognized for some
time. In 195^-j the Bureau of Reclamation included a drain
in its feasibility report of the San Luis Unit. In 1957:,
the California Department of Water Resources initiated an
investigation to assess the extent of salinity and high
ground water problems and to develop plans for drainage
and export facilities. The Burns-Porter Act,, in 1960,
authorized San Joaquin Valley drainage facilities as part
of the State Water Facilities.
The authorizing legislation for the San Luis Unit
of the Bureau of Reclamation's Central Valley Project.,
Public Law 86-488, passed in June 1960, included drainage
facilities to serve project lands. This Act required that
the Secretary of the Interior either provide for construc-
ting the San Luis Drain to the Delta or receive satisfac-
tory assurance that the State of California would provide
a master drain for the San Joaquin Valley that would ade-
quately serve the San Luis Unit.
Investigations by the Bureau of Reclamation and
the Department of Water Resources revealed that serious
drainage problems already exist and that areas requiring
subsurface drainage would probably exceed 1,000 .,000 acres
by the year 2020. Disposal of the drainage into the
Sacramento-San Joaquin Delta near Antioch, California., was
found to be the least costly alternative plan.
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Preliminary data indicated the drainage water
would be relatively high in nitrogen. The then Federal
Water Quality Administration conducted a study to deter-
mine the effect of discharging such drainage water on the
quality of water in the San Francisco Bay and Delta. Upon
completion of this study in 196? j> the Administration's
report concluded that the nitrogen content of untreated
drainage waters could have significant adverse effects
upon the fish and recreation values of the receiving
waters. The report recommended a three-year research
program to establish the economic feasibility of nitrate-
nitrogen removal.
As a consequence,, the three agencies formed the
Interagency Agricultural Wastewater Study Group and
developed a three-year cooperative research program which
assigned specific areas of responsibility to each of the
agencies. The scope of the investigation included an
inventory of nitrogen conditions in the potential drainage
areasj possible control of nitrates at the source,, predic-
tion of drainage quality^ changes in nitrogen in transit,,
and methods of nitrogen removal from drain waters including
biological-chemical processes and desalination.
vi
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TABLE OF CONTENTS
Page
ABSTRACT ill
BACKGROUND v
CHAPTER I - CONCLUSIONS 1
CHAPTER II - INTRODUCTION „ 3
CHAPTER III - PROCESSES STUDIED 7
Nitrogen Removal Systems 8
Algae Stripping 8
Bacterial Denitrification 9
Desalination 10
CHAPTER IV - RESULTS „ . . . 11
Algae Stripping 11
Growth 11
Nutrient Additions .... 11
Mixing 11
Detention Time 12
Culture Depth 12
Biomass Control 12
Laboratory Growth Studies 12
Algal Harvesting „ 13
Laboratory Tests 13
Concentration 14
Dewatering „ 14
Drying 15
Disposal 15
Bacterial Denitrification 15
Anaerobic Filters 15
Media 16
Temperature 16
Long-term Operation 16
VI1
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TABLE OF CONTENTS (Continued)
Methanol Requirement 17
Special Studies 0 . if
Anaerobic Deep Ponds „ . . 17
Effect of Treatment on Removal of Algae Growth
Potential 18
Soil Ponds 18
Botulism Studies 19
Desalination 19
Reverse Osmosis 19
Electrodialysis 20
CHAPTER V - PROCESS EVALUATION 21
Nitrogen Removal „ 21
Process Configuration „ 21
Cost Estimates „ 22
ACKNOWLEDGMENTS 25
LIST OF REFERENCES 27
PUBLICATIONS 29
VI11
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LIST OF FIGURES
Figure
Number Page
1 Location of the Interagency Agricultural
Wastewater Treatment Center 4
2 Agricultural Wastewater Treatment Center . . 6
3 Organization Chart - Interagency Agricultural
Wastewater Treatment Center 6
4 Seasonal Variation in Total Dissolved Solids
and Nitrate-Nitrogen in Agricultural Drainage
Water Available at Wastewater Treatment
Center 7
5 Flow Diagram of Algal Stripping Plant ... 22
6 Flow Diagrams of Bacterial Denitrification
Plant - Pond and Filter Configurations ... 23
IX
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LIST OP TABLES
Table
Number
Approximate Effluent Nitrogen Concen-
trations Expected from the Various
Processes Studied at the IAWTC 21
Estimated Treatment Costs for Removal of
Nitrogen from San Joaquin Valley Tile
Drainage 24
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CHAPTER I
CONCLUSIONS
1. Algal growth and harvesting (algae stripping) and bac-
terial denitrification are technically feasible methods of
removing nitrate-nitrogen from subsurface agricultural tile
drainage in the San Joaquin Valley. With an influent concen-
tration of 20 mg/1 total nitrogen., the algae stripping process
will produce an effluent containing from 3-5 mg/1 total nitro-
gen (depending on season) and bacterial denitrification an
effluent of 2 mg N/l or less.
2. Laboratory algal growth assays comparing treated (either
process) and untreated tile drainage mixed with potential
receiving waters showed that nitrogen removal effectively
reduced the biostimulatory nature of the waste.
3. Preliminary cost estimates for the system described in
this report range from $90 per million gallons (about $30
per acre-foot) for bacterial denitrification to $135 per
million gallons ($^5 per acre-foot) for algae stripping.
These figures are based on the results of technical feasi-
bility studies and may be revised after 1970 operational
studies.
4. Desalination of tile drainage by reverse osmosis or
electrodialysis was found to be technically feasible although
cost analysis indicated that the direct reuse of agricultural
drainage after desalination was not economically feasible.
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CHAPTER II
INTRODUCTION
This report summarizes the results of an investiga-
tion of the technical feasibility of removing dissolved nitro-
gen (95 percent in the nitrate form) from subsurface agricultural
tile drainage in the San Joaquin Valley of California. The
investigation was conducted from 1967 through 1969 at the
Interagency Agricultural Wastewater Treatment Center (J_A¥TC),
located about 45 miles from Fresno, California,, near the town
of Firebaugh (see Figure 1). The overall investigation at
the Center was divided into the general areas of nitrogen
removal by biological systems (algae stripping and bacterial
denitrification), effect of nitrogen removal on the biostimu-
latory nature of the drainage water, and the use of desalination
(reverse osmosis and electrodialysis) to remove minerals dis-
solved in the drainage with special interest in nitrate and
boron removal. The data and conclusions of the individual
technical feasibility studies have been published (Brown, 1971 j
Sword, 1971a; Tunzi, 1971; and Sword, 1971b) are available to
readers interested in more detail than found in this summary
report. The results of 1970 algae stripping and bacterial
denitrification operational studies will be published in the
fall of 1971.
The Background section of this report provides the
chronological order of events leading to the development of
the extensive study of subsurface agricultural drainage in the
San Joaquin Valley. After publication of the results of the
study by the Federal Water Pollution Control Administration,
now the Environmental Protection Agency (EPA), entitled "Effect
of the San Joaquin Master Drain on the water quality of the
San Francisco Bay and Delta" (Federal Water Pollution Control
Administration 1967), representatives of several agencies,
including D¥R, USER, and EPA, met in Los Banos, California,
to develop a coordinated program for studying the entire drain-
age problem in the San Joaquin Valley. At this meeting, the
Interagency Nitrogen Removal Group (USER, EPA, and DWR) was
organized and two areas of investigation were assigned to
the IAWTC -- nitrogen removal by biological systems (algal
growth and harvesting and bacterial denitrification) and total
dissolved solids and boron removal (desalination).
Although the actual Center was not developed until
1967, nutrient removal studies had been planned by DWR as
early as 1964. In 19&3, D¥R retained Dr. William J. Oswald
(Sanitary Engineer, University of California, Berkeley),
Dr. Clarence G- Golueke (Microbiologist, University of
California, Berkeley), and Dr. Donald G. Crosby (Toxicologist,
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FIGURE I. LOCATION OF INTERAGENCY AGRICULTURAL
WASTEWATER TREATMENT CENTER
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University of California, Davis) to evaluate the feasibility
of algal growth and harvesting (popularly known as "algae
stripping") as a treatment method nitrogen removal for San
Joaquin Valley agricultural wastewaters. Their report stated
that algae stripping was probably economically feasible and
recommended that pilot-scale studies using subsurface agri-
cultural wastewaters be undertaken in the San Joaquin Valley.
The Department reviewed the feasibility report and accepted
the recommendation that prepilot studies be initiated at a
site on the west side of the San Joaquin Valley. Land for
the site was acquired from the Bureau of Reclamation in 1966.
Construction of the algae stripping plant began in 1967 and
was completed in early 1968.
The Department of Water Resources also retained
Dr. Perry L. McCarty (Sanitary Engineer,, Stanford University,
Palo Alto) early in 1966 to evaluate the effectiveness of
anaerobic denitrification as a treatment method. Dr. McCarty's
report indicated that anaerobic denitrification in deep ponds
would work and was economically competitive with algae strip-
ping. He recommended that large-scale studies be undertaken
in the San Joaquin Valley. Preliminary studies of this pro-
cess were started during the summer of 1967. In addition to
the work at Firebaugh, the EPA,, in cooperation with the Los
Angeles County Sanitation District., was using sewage as a
substrate to study bacterial denitrification. These studies
were begun in 1966.
The remaining process investigated at the Center,
desalination, was begun in 1967 under the sponsorship of the
Office of Saline Water with the EPA as the responsible agency.
The purpose of this research was to define the problems
involved in removing dissolved minerals from agricultural tile
drainage.
Figure 2 contains an aerial photograph of the IAWTC
after all of the facilities had been fully developed. The
research at the Center was conducted by an interagency group
of engineers, biologists, chemists, and technicians under the
general guidance of the Board of Directors consisting of: the
Director, Region 2, USER; the Director, Pacific Southwest
Region, EPA; and the Director, California Department of Water
Resources. A Technical Coordinating Committee consisting of
project directors from each of the responsible agencies pro-
vided direct technical direction. A Treatment Consulting
Board made up by Drs. Oswald, Golueke, and McCarty, reviewed
the overall work of the project and provided operating guide-
lines for specific areas of study. The organization of the
Center is illustrated in Figure 3.
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a -TILE DRAINAGE SUMP
b-LIGHTBOX TRAILER
c - COVERED STORAGE POND
d-RAPID GROWTH POND
e-LABORATORY BUILDING
-SEPARATION STUDIES AREA
g-MINIPOND GROWTH UNITS
h-SMALL SCALE (I8"DIA.)
ANAEROBIC FILTERS
i-PILOT SCALE (IO'XIO'1
ANAEROBIC FILTERS
j - COVERED ANAEROBIC POND
h - UNCOVERED ANAEROBIC POND
FIGURE 2 -AGRICULTURAL WASTEWATER TREATMENT CENTER
1
LABORATORY
1
CHEMIST
(EPA)
PROJECT PRO,.
(DWR) (E
SECRETARY
(EPA)
191 COORDIN*
p™R (USBF
ITOR
i)
DATA
PROCESSING
tNWNthR (tPA)
TECH (DWR)
ALGAE STRIPPING
ALGAE GROWTH
BIOLOGIST
(DWR)
1 1
CHEMIST
(DWR)
BIOLOGIST
(EPA)
1 1
LAB AID
(DWR)
LABORER
(DWR!
1 1
LAB AID
(DWR)
LAB AID
(DWR)
ALGAE HARVESTI
ENGINEER
(DWR)
1
ENGINEER
(USBR)
1
ENGR TECH
(DWR)
BOARD
CONSULTANTS
BACTERIAL DENITRIFICATION
AND
DESALINATION
*JG
ENGINEER
(EPA)
1
TECH
(USBR)
1
TECH
(USBR)
1
TECH
(USBR)
TECH
(USBR)
FIGURE 3-ORGANIZATION CHART-INTERAGENCY AGRICULTURAL WASTEWATER TREATMENT CENTER
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CHAPTER III
PROCESSES STUDIED
This section provides general description of the
algae stripping,, bacterial denitrification, and desalination
processes studied at the IA¥TC. The methods used in the
studies on the biostimulatory effect of the treated and
untreated drainage waters on algae growth in Sacramento-San
Joaquin Delta will be described in the Results section. More
detailed descriptions of the systems can be found in the
individual reports cited previously.
As much as possible, the tile drainage water was
used without any alteration; however, annual fluctuations in
water quality and quantity caused by irrigation practices in
the overlying fields often made this impossible. As shown
in Figure 4, total dissolved solids (TDS) and nitrate in the
tile system varied considerably from year to year.
10,000
J 8,000
_
o
V)
£ 6,000
o
CO
CO
< 4,000-
h-
o
2,000
TOTAL DISSOLVED SOLIDS (mg/l)
/ V' \ NITRATE-NITROGEN (mg/l)'
/ \
r
40
-30
-20
LL!
C3
O
CCL
I
UJ
I-
<
-10
JAN
JUL
1966
JAN
JUL
1967
JAN
JUL
1968
JAN
FIGURE 4-SEASONAL VARIATION IN TOTAL DISSOLVED SOLIDS AND
NITRATE-NITROGEN IN AGRICULTURAL DRAINAGE WATER
AVAILABLE AT THE WASTEWATER TREATMENT CENTER
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These changes caused some operational problems. During the
periods of low TDS concentrations and accompanying low
nitrogen levels, nitrogen was added as sodium nitrate to make
a final concentration of about 20 mgN/1 (milligrams nitrogen
per liter). During periods of low winter flow, the drainage
from the sump was mixed with water from the Delta-Mendota
Canal (DMC). The mixture was used in the bacterial denitri-
fication studies only after experimentation had shown that
results with the mixed waters were comparable to those in
which pure drainage was used, providing nitrogen levels were
similar. In the latter part of the desalination work, drain-
age was blended with DMC water to provide a constant TDS of
about 3,000 mg/1, thus eliminating salinity as a variable.
Nitrogen Removal Systems
Algae Stripping
Algae stripping is an assimilative nutrient removal
process involving three phases. In the first, algae growth
(with incorporation of the nutrient into cellular material)
is encouraged by creating the most favorable environmental
conditions. Shallow outdoor ponds were provided with some
means of mechanically mixing the culture. Any nutrients
other than those to be removed may be added to the growth
medium and only the undesirable nutrients will limit growth.
The second phase involves the removal of the algal biomass
from suspension by some harvesting process, e.g., sedimenta-
tion, and then the biomass is dried to the desired moisture
content. In the third phase the dried algal product must
then be disposed of, preferably by utilization in a way which
reduces the cost of the treatment system. Possible means of
disposal include incineration, landfill, fertilizer,
high-protein food supplement, or as a soil conditioner.
In the growth phase, algae, predominantly of the
genus Scenedesmus, were grown in three levels of culture --
laboratory,small outdoor ponds (miniponds), and a larger
1/4-acre growth pond. The effect of various factors was first
screened in the laboratory and small ponds, and then the
optimum levels of the various factors were combined in opera-
tion of the larger pond. Algal harvesting studies were
divided into laboratory and field (pilot-scale) unit evalua-
tion, with the laboratory studies used to determine the most
effective coagulant dosage for the sedimentation-flocculation
unit. Also evaluated were methods of dewatering a 3- to 5-
percent (by weight) algal slurry to about 20 percent solids
and drying the resultant material to about 90 percent solids.
The study of disposal was limited to a literature search and
to supplying the dried algal product to interested companies.
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The specific objective of the algal growth and
harvesting investigation at the IAWTC was to produce an
effluent containing 2 mg/1 or less of total nitrogen,, a limit
recommended by the 1967 EPA report. This effluent nitrogen
was composed of dissolved (both organic and inorganic) and
particulate (incorporated in cellular tissue) forms of the
element; thus,, total nitrogen removal relied on growth and
assimilation of the dissolved nitrate and harvesting of the
algal cells from the liquid phase. For example, to remove
90 percent of the nitrogen from an influent containing 20 mg/1
nitrogen by the algal process would require 95 percent assimi-
lation by the algae and subsequent removal of 95 percent of
the algal biomass. To achieve this objective, growth studies
were designed to determine optimum conditions for nitrogen
assimilation and separation studies were designed to remove
algal biomass while maintaining costs at an economical level.
Bacterial Denitrlfication
In contrast to algae stripping, bacterial denitri-
fication is a dissimilatory nitrogen removal process in which
most of the incoming nitrate is converted to nitrogen gas;
however, a small fraction of the nitrate does enter into the
production of bacterial protein. The bacterial denitrifica-
tion process requires anaerobic, or nearly anaerobic, condi-
tions and the presence of an organic carbon energy source,
such as methanol. Under these conditions, the bacteria can
use nitrates and nitrites as terminal electron acceptors in
the oxidation of the organic material. The overall reaction
shows nitrate being reduced to nitrite and then to nitrogen
gas; however, identification of the bacterial group or groups
responsible for specific steps in the pathway was not attempted
in the current study.
Dr. McCarty's original feasibility study investigated
the use of several organic carbon sources for the denitrifica-
tion process and found that both acetic acid and methanol
were satisfactory compounds. Because it is available in
large quantities, synthetically produced methyl alcohol, or
methanol, was used in all denitrification studies at the
IAWTC.
Two process configurations of the anaerobic denitri-
fication system were evaluated at the Center -- deep ponds and
filters. In deep ponds, methanol was mixed with the influent
tile drainage, and the developing bacterial culture was either
free-floating or attached to the sides of the container. The
pond process was first tested at the Center using 3-foot
diameter simulated deep ponds with-water depths ranging from
6 to 11 feet. After these data had shown that the process
was feasible, two larger earth-lined ponds having surface
areas of 10,000 and 2,500 square feet and water depths of
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14 feet were constructed at the site. Both ponds had pro-
visions for recycling bacterial biomass from the bottom of
the pond to the influent. The larger of the two units was
completely covered with styrofoam planking to minimize re-
oxygenation of the water by algae and by wind mixing. The
other pilot-scale pond remained uncovered.
In the filter configuration of the anaerobic pro-
cess, methanol mixed with tile drainage flowed upward through
an enclosure filled with an inert medium, small gravel, for
example. The purpose of this medium was to provide a sub-
strate to which the bacteria could attach and thus lengthen
the solids retention time of the system (length of time a
particle remained in the container). Four sizes of containers
were used in the evaluation of the anaerobic t/ilt-er process at
Firebaugh -- 4-inch diameter PVC pipes, 18-inch diameter
concrete pipes, 3-f°°t diameter concrete pipes, and a 10-foot
wide by 10-foot long pilot-scale filter. Media depth in all
units was 6 feet.
The objective of the denitrification study was also
to achieve an effluent containing less than 2 mgN/1; although
in this process, contrasted to algae stripping, the effluent
contained only small amounts of particulate organic nitrogen.
Desalination
Two desalination methods were tested during this
study -- reverse osmosis and electrodialysis. Package plants
were supplied by OS¥ -- an Aerojet General reverse osmosis
unit and an Ionics, Inc., electrodialysis unit. Representa-
tives of the manufacturers provided assistance in the instal-
lation and initial operation of the units. The principles
involved in the operation of these units will be explained as
they pertain to the results obtained in the studies.
The primary objective of desalination was to obtain
some operational data on the use of existing equipment to
demineralize agricultural tile drainage. Reduction of dis-
solved nitrogen was a secondary objective. This part of the
investigation was also designed to provide some preliminary
cost data and an estimate of removal rates of boron and
nitrate.
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CHAPTER IV
RESULTS
This section discusses algae stripping, bacterial
denitrification, soil ponds (so-called "symbiotic" ponds),,
effect of treatment on algal growth potential, botulism
studies, and desalination. Results are based on data col-
lection prior to January 1, 1970, although some algal har-
vesting results obtained after this date are included, to
complete missing areas of data.
Algae Stripping
Growth, harvesting, and disposal of the algae were
studied under the general topic of algae stripping. In
general, the studies at the IAWTC have shown that algal
growth and. harvesting is a technically feasible means of
removing nitrate-nitrogen from subsurface tile drainage in
the San Joaquin Valley. The results from specific areas of
the algae stripping studies are summarized in the following
paragraphs.
Growth
Tile drainage will support extensive algal growth,
providing environmental conditions are made optimum for such
growth. The effect of several chemical and physical factors
on algal growth was studied using laboratory and outdoor
cultures. The following discussion of these factors includes
the best estimates for their optimum levels in outdoor
cultures.
Nutrient Additions. Three nutrients -- phosphorus,
iron, and carbon dioxide-- appeared necessary to support the
required growth of Scenedesmus in agricultural tile drainage.
The phosphorus requirement was about 2 mg/1 and was necessary
during all seasons of the year. During the spring, summer,
and early fall, the addition of 5 percent C02 enhanced algal
growth and nitrogen assimilation over non-C02 ponds. The
Influent-dissolved inorganic carbon appeared to be an adequate
carbon source d.uring the winter months. Iron also seemed
to be a seasonal requirement. Routine addition of 2 to 3 mg/1
of this substance may be desirable because of the beneficial
effect iron has on algal harvesting.
Mixing. Mixing results obtained before carbon
dioxide additions were tested showed that four days of day-
light mixing at velocities from 0.25 to 0.50 foot per second
were required for maximum nitrogen assimilation. Further
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studies of various combinations of carbon dioxide and mixing
indicated that mixing alone had little effect on nitrogen
assimilation,, and that maximum nitrogen assimilation could
be obtained by injection of a mixture of CO^ and compressed
air into an otherwise unmixed pond. Because mixing is a
major cost component of algal treatment, 1970 operational
studies will emphasize this facet of the treatment process.
Detention Time. Provided that inorganic phosphorus
was supplied to the algal cultures, detention time was nor-
mally the most important variable studied in an individual
minipond run. After January of 1969, detention times ranging
from 3 to 16 days were used in outdoor studies. Three dif-
ferent detention times were used, in each run of 4 to 6 weeks'
duration. The detention times, based on previous data, were
selected to include flow-through rates which bracketed the
predicted optimum detention time. Theoretical detention times
required for maximum nitrogen assimilation varied from 5 to
16 days and appeared to be directly related to pond tempera-
ture between 12 and 25°C and independent of temperature
between 25 and 33°C. Culture depth and biomass control also
significantly affected detention time.
Culture Depth. Culture depths of 8, 12, and 16
inches were studiecTJarid maximum nitrogen assimilation
occurred at the 8-inch culture depth. Assimilation rates in
cultures with 12-inch depths comparable to those of 8 inches
required a three- to four-day longer detention time. Compar-
ison of the difference between nitrogen assimilation in the
two extreme depths studied, 8 and 16 inches, showed that the
effect of depth was more pronounced during the winter months,
and was directly correlated with available light.
Biomass Control. Biomass control, or regulation of
in-pond algal biomass, wa~s- studied when algal cells appeared
to accumulate in the growth units. A sedimentation tank was
attached to one of the miniponds to remove the older, heavier
algal cells and suspended soil and chemical precipitates.
These studies showed that the summer detention times neces-
sary for attaining the desired level of nitrogen removal
(less than 2 mg/1 total effluent nitrogen) would be about
five days, or about three days less than in comparable ponds
without biomass control. Some control mechanism will be
needed in an operational algal treatment plant, perhaps
settling areas in the ponds themselves.
Laboratory Growth Studies. Laboratory growth
studies were used to gain valuable information concerning
such factors as nutrient additions, desirable algal species,
and comparisons of growth rates in water from different tile
drainage systems. Some discretion was required in the inter-
pretation of results from these studies because environmental
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conditions in the laboratory were usually more conducive to
algal growth than such conditions in outdoor cultures. Thus.,
in the laboratory some compounds caused a dramatic effect on
algal growth,, but in outdoor units their effect was masked
because culture growth was limited by light, temperature,, etc.
The difference is demonstrated by the result of adding iron
to the Scenedesmus cultures. Iron was necessary for maximum
nitrogen assimilation in practically every light study but
was only seasonally required in outdoor cultures.
Two series of laboratory studies were used to com-
pare rates of nitrogen removal in water from various tile
systems in the Valley. The results of these studies showed
that water from the Alamitos sump (the tile drainage system
providing water used at the IAWTC) exhibited algal growth
similar to that shown by the other tile effluents and that
phosphorus was necessary to all of the waters. There were
more seasonal variations in the water quality from Alamitos
sump (because of summer rice culture) than in most tile sys-
tems in the Valley., and there were indications that the algal
growth potential of the Alamitos water decreased during the
summer. This fluctuation in water quality may have led to
conservative estimates of the potential of algae stripping
as a mechanism for removing nitrate from drainage water.
Algal Harvesting
Harvesting of algal biomass is divided into three
phases -- concentration,, dewatering, and drying,, all of which
differ in the amount of moisture remaining in the algal
product. Studies demonstrated that algae can readily be
separated from agricultural tile drainage and concentrated
to 1 to 2 percent solids (by weight) by either coagulation-
flocculation and sedimentation with any of several chemical
coagulants or by use of a special configuration rapid sand
filter (Sanborn filter) with backwashing. The slurry result-
ing from this concentrating process can then be dewatered to
about 10 to 20 percent solids by vacuum filtration or by self-
cleaning centrifugation. Other concentrating and dewatering
processes,, microscreen and upflow clarifier, were tested with
indefinite results, either because of operational problems
or because of incorrect design for the type of material to
be separated.
Laboratory Tests. Laboratory jar tests were con-
ducted to determine the effectiveness of various mineral
coagulants (lime, alum, and ferric sulfate) and polyelectro-
lytes in achieving coagulation of the alga Scenedesmus from
growth pond samples. These studies showed the additions of
lime, alum, or ferric sulfate could effect 90 to 95 percent
removal of the suspended solids from samples containing from
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100 to 800 mg/1 total suspended solids. This level of re-
moval was attainable during all seasons of the year; however^
the required concentration of mineral coagulant varied with
changes in operation of the growth unit. When iron (FeClo)
was added to the rapid growth pond as an algal nutrient., the
concentrations of chemical required for removal of approxi-
mately* 95 percent of the influent suspended solids ranged
from 5 mg/1 for ferric sulfate, to 20 mg/1 for alum,, and
40 mg/1 for lime. These concentrations are compared to
80 mg/1, 100 to 140 rag/1, and 180 to 200 mg/1 additions for
the same compounds when iron was not being added to the
growth pond.
Approximately 60 anionic, cationic, and nonionic
polyelectrolytes were tested alone and with the mineral coag-
ulants to evaluate their effectiveness in the coagulation-
flocculation step of algal harvesting. Seventeen compounds
were found to aid coagulation at costs comparable to those
found for the mineral coagulants. The effectiveness of the
polyelectrolytes was also influenced by operation of the
growth units. One compound,, Cat-Floe,, was completely inef-
fective when the growth units did not receive daily additions
of iron; but,, after iron was added, more than 95 percent of
the suspended solids could be removed by the addition of less
than 0.5 mg/1 of the polyelectrolyte.
Concentration. A shallow sedimentation unit with
inclined tubesin theSedimentation chamber (a Water Boy unit
manufactured by Neptune Microfloc of Corvallis, Oregon) was
tested using chemical coagulant dosages determined by labora-
tory tests. Up to 97 percent of the total suspended solids
were removed in the sedimentation area of this unit, with
another 2 to 3 percent removed by a mixed-media upflow filter
which followed sedimentation. After the filter had been
taken out of the unit, 95 to 97 percent of the suspended
solids were consistently removed. The algal slurry from this
unit contained 1 to 2 percent suspended solids. A second
concentrating device, a Sanborn rapid sand filter assembled
by Bohna Engineering of San Francisco, also removed about
95 percent of the suspended solids and produced an algal
slurry containing 1 to 3 percent solids. Other units (micro-
screen, upflow clarifier, and centrifuges) were tested, as
concentration devices but were not found to be as effective
or reliable as the sedimentation and rapid sand filter systems,
Dewatering. An Eimco vacuum filter produced an
algal cake containing about 20 percent solids from an influ-
ent with about 0.3 to 3 percent solids. This level of
removal was obtained using a mult if ilament nylon belt., ,a
vacuum of 20 to 25 inches of mercury and a solids loading on
the belt of up to 17.,000 milligrams per square foot per minute.
A self-cleaning De Laval centrifuge produced an algal product
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which contained about 10 to 12 percent solids and removed up to
95 percent of the influent algae (influent concentrations rang-
ing from 500 to 30,000 mg/1). This centrifuge was found to be
more effective than either a solid-bowl or nozzle-type unit.
Drying. The algae were normally dried in the open
for three to four days on cloth toweling supported by wire
frames. A layer of algal slurry 1/2-inch to 3/4-inch thick
had dried to about 85 to 95 percent -solids at the end of this
time. This moisture content allowed safe storage of the
material. Studies also showed that the algae could be dried
in about two days by spreading the slurry in a 1/2-inch
thick layer on asphalt pavement. Pavement drying is easily
adaptable for mechanical spreading and collection of the
product. One algal sample containing about 15 percent solids
was spray-dried by the De Laval Company at the company's
test facilities. The operators of the test equipment experi-
enced no problems in attaining the desired level of moisture
in the product.
Disposal. Based on a literature review of the
possible uses for an algal product and predictions of com-
mercial demands, a market can probably be developed for an
algal product which will retail for about $80 to $100 per
ton. The question of marketability can be answered more
completely when the companies receiving samples of the product
algae report their findings. The high ash content (30 to 50
percent) of product algae from these studies may preclude its
use as livestock food but it may be acceptable as a protein
supplement for fowl or as a soil conditioner. Modification
of the harvesting process to include an in-pond settling
process to remove soil particles and chemical precipitates
may result in two by-products, one containing 10 percent ash
and the other about 50 percent ash.
Bacterial Denitrification
The field feasibility studies of anaerobic denitri-
fication of agricultural tile drainage, completed in December
1969., were designed to investigate nitrogen removal by anaero-
bic filters and covered and uncovered anaerobic deep ponds.
The experimental work demonstrated that removal of nitrogen
from agricultural tile drainage is technically feasible by
means of bacterial denitrification in anaerobic filters and
covered anaerobic ponds.
Anaerobic Filters
The anaerobic filter was tested to determine the
effect of media, temperature, and long-term operation on
filter performance. The following results were obtained
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primarily from the l8-inch diameter filters; the pilot-scale
filter had not "been operated extensively enough for adequate
evaluation.
Media. Of the several media tested, including
sand,, activated charcoal, volcanic cinders, and various sizes
of aggregate, it was concluded that one-inch diameter rounded
aggregate was the most suitable for denitrification of tile
drainage in upflow anaerobic filters. The use of smaller
diameter aggregate, as well as sand and activated charcoal,
eventually led to retention of large bacterial masses in the
filters. This bacterial buildup caused high influent pressures
and resulted in short-circuiting of water through the filter.
Conversely, the larger medium was not effective because the
filter did not retain the bacterial cells and these units
required longer hydraulic detention times for nitrogen removal.
An artificial plastic medium (Dow Surfpac) was tested with
unfavorable results in that sufficient bacterial biomass was
not retained for efficient filter operation.
Temperature. The effects of various temperatures
on performance of the anaerobic filters were determined by
observation of filter units under actual operating tempera-
tures, and construction of a small filter in a temperature-
controlled environment. In the small filter (4-inch diameter.
6-foot length), when the temperature was lowered from 20°C to
10°C, the denitrification efficiency (percent nitrogen removed)
dropped from above 95 percent to about 60 percent. Hydraulic
detention times of one and two hours in the 18-inch diameter
filters (6-foot bed depth) produced effluents containing
2 mg/1 or less total nitrogen until water temperatures fell
below l4°C. Below this temperature, only the two-hour deten-
tion time filters met the proposed effluent criteria. Samples
taken at various media depths in the units showed that as the
temperature dropped, more of the filter area was required to
achieve the same degree of nitrogen removal; for example, at
temperatures above l6°C the two-hour detention time filter was
able to achieve 90 percent nitrate reduction (20 mg/1 influent)
in one-fourth of the filter, but at temperatures of about
12 to l4°C, three-fourths of the bed was required for the same
level of removal.
Long-term Operation. Long-term experimentation with
anaerobic filters has shown that in time excessive bacterial
growth within the filters will cause definite operational
problems. Such growth increases effluent ammonia and organic
nitrogen, presumably from decomposition of the bacteria,
although the decomposition was only a problem in the warmer
summer months. The main detrimental effects of the excess
biomass are hydraulic changes within the filter such as short-
circuiting and excessive head loss. Further experimentation
has been conducted in 1970 to determine the most effective and
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economical method of controlling and/or removing excess
bacterial growth from the filters. The l8-inch diameter
filters have been effectively flushed by a mixture of air
and water forced through the units. This process removes
the biomass but also disrupts the filter's performance for
several days thereafter.
Methanol Requirement. The amount of methanol
required to reduce 20 mg/1 of NC>3-N is calculated to be
about 56 mg/1. (This assumes that the dissolved oxygen
concentration is 8 mg/1 and that the amount of methanol
based on stoichiometric reactions will have to be increased
by about 30 percent to allow for bacterial growth.) In
actual operation,, the practical lower limit was found to be
closer to 65 mg/1. This concentration was necessary for
both filter and pond operation.
Special Studies. Results of studies on algal-
laden water used as an influent to an anaerobic filter have
shown that the algae do not Interfere with nitrate-nitrite
reduction, but the accumulation of algal cells within the
filter and the decomposition thereof, along with suspended
algae passing through the filter, eventually produced effluent
concentrations of organic and ammonia nitrogen i-n the range
2 to 5 mg/1.
Anaerobic Deep Ponds.
The large uncovered anaerobic pond never produced
an effluent containing less than 2 mg/1 total nitrogen,
although during the summer months concentrations from 3 to
6 mgN/1 were obtained at 10 days'detention time. The rela-
tively low nitrogen removal efficiency undoubtedly resulted
from reaeration of the water by wind mixing and photosynthetic
oxygen production.
The pilot-scale covered pond reduced an influent
nitrate-nitrogen concentration of 20 mg/1 to 2 mg/1 or less
of total nitrogen at temperatures as low as l4°C at a 15-day
theoretical hydraulic detention time. It produced 2 mg/1 or
less total nitrogen effluent concentration at an actual
hydraulic detention of 8.2 days at temperatures between 20
and 22°C; however, an actual detention time of five days at
this temperature range resulted in an average effluent nitro-
gen concentration of approximately 4 mg/1. In the experiments
that have been completed thus far, successful operation at
temperatures below l4°C has not been achieved, but continuing
experimentation is expected to show that the 2 mg/1 total
nitrogen criterion can be met during the colder months of the
year.
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Effect of_ Treatment on Removal of Algal Growth Potential
Laboratory experiments were conducted to determine
the effect of nitrogen removal on the biostimulatory nature
of the subsurface agricultural tile drainage. In these
experiments, algal growth was measured in various proportions
of treated and untreated tile drainage mixed with water from
the Sacramento-San Joaquin Delta near Antioch, a proposed
discharge location of an agricultural drain from the San
Joaquin Valley. The additions were 1., 10, and 20 percent
drainage by volume and were designed to simulate expected
ranges of concentration near the outfall. Growth responses
of the indigenous Delta algae in the culture flasks were
then measured by changes in chlorophyll fluorescence and
cell counts.
In each of the mixtures of tile drainage and Delta
water tested, the bioassay responses of the treated water
mixtures were significantly lower than those of mixtures of
untreated tile drainage and Delta water. Spiking the treated
water back to the original nitrogen concentration resulted
in bioassay responses statistically equal to"those caused by
the untreated water. Comparison of effluents from algae
stripping (growth and harvesting) and bacterial denitrifica-
tion indicated that, if the inorganic nitrogen concentrations
were similar, the algae growth responses of the cultures were
in the same range.
The results of this study demonstrated that, in
laboratory cultures, nitrogen removal by the biological
processes studied at the IA¥TC effectively reduced the bio-
stimulatory nature of the waste to Delta waters. The addi-
tion of 10 and 20 percent of effluents containing 2 mgN/1 or
less Delta water yielded growth responses comparable to con-
trol cultures containing Antioch water only.
Soil Ponds
The one removal process In which relatively little
definitive work was accomplished during this investigation
was that of soil-lined ponds. This type of process undoubtedly
involves a combination of algal and bacterial metabolic path-
ways. What probably happened in these unmixed ponds was that
algal growth partially removed the dissolved nitrogen; then
the algae settled and the anaerobic decomposition of the algal
biomass reduced the remaining nitrate to nitrogen gas. Data
from the two units operated at the IAWTC showed that for 1969,
the average nitrate removal in the soil ponds was about
85 percent of that obtained in the best conventional miniponds
(mixing, iron and C02 additions, etc.), and that the average
total effluent nitrogen was usually less than 3 mg/1. The soil
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ponds may be comparable to a system from another nitrogen
removal process that Involved passing the nitrogen-enriched
water over a field of water grass. A Bureau of Reclamation
study of this latter process indicated that substantial
amounts of nitrogen were removed by the grass plots, but the
exact mechanisms were not identified. The algal counts in
the flooded field were uniformly low and the water remained.
aerobic at all times (at least as measured by the methods
used). ^The results of the Bureau of Reclamation's study will
be published by the Interagency Nitrogen Removal Group as part
of the series on nitrogen removal (Williford and Cardon, 1971).
During the 1970 calendar year, studies began at
the IAWTC to determine the types of biological systems involved
in the soil pond system and to evaluate the process in larger
units.
Botulism Studies
The California Department of Fish and Game conducted
studies at the IAWTC to determine the potential for botulism
outbreaks in the types of units tested at the Center. The
studies concluded that the algal ponds and uncovered anaerobic
ponds could develop botulism problems, especially if large
invertebrate populations were to develop. Based on these and
related Department of Fish and Game studies,, specific recom-
mendations were proposed to eliminate the potential problem.
All open ponds should have steep sides, a minimum
of shoreline, and as great a depth as possible. Before flooding,
all vegetation should be burned, and after flooding vegetation
on the levees should be controlled. Fluctuation of water level
should be minimized and the ponds not allowed to become stag-
nant for any length of time. All these management practices
are designed to eliminate large invertebrate mortalities which
can serve as food sources in an environment conducive to the
development of Clostridium botulinum.
Desalination
Reverse Osmosis
One reverse osmosis unit was evaluated at the
Center; however, two membrane stacks (each stack consisted
of several membranes) were tested for removal of total dis-
solved solids and in particular, their ability to remove boron
and nitrate. The membranes used in this type of desalination
were designed to be permeable to water but not to most ions.
In operation, pressure applied to the highly saline water on
one side of the membrane forced fresh water across the
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membrane} leaving most of the salts behind. The first type
of membrane tested at Firebaugh was designed to allow little
penetration of salts through the membrane and required a
high pressure, 750 pounds per square inch (psi), to obtain
the desired demineralization. The first membrane also had
a low product flow per unit of membrane area (flux). When
operating at peak performance,, the unit containing this
membrane stack removed over 90 percent of the influent TDS
(influent range of 3^000 to 7.,000 mg/1 'TDS); however, boron
and nitrate were reduced only about 27 percent. About 37
percent of the influent flow was recovered as low salinity
product. Operation of the reverse osmosis unit required
prefiltration of the influent., pH adjustment to prevent pre-
cipitation of calcium carbonate, and treatment to prevent
precipitation of calcium sulfate. The efficiency of the
first stack began to decrease after about five months.,
apparently because of biological fouling and subsequent
membrane deterioration.
The second stack was designed to have a higher
product flux with lower salt rejection characteristics
and a lower operating pressures (about 350 psi). This
stack was operated on a constant salinity water supply
(3,000 mg/1 TDS) prepared by blending irrigation canal
water with the tile drainage. Initial evaluation of this
stack showed that the unit reduced the TDS by about 85 per-
cent but that nitrate and borate ions were not being removed
to any measurable extent. Product recovery averaged about
40 percent with this stack, an unexpectedly low recovery
rate that was probably caused by faulty assembly of the
stack components.
Electrodialysis
The electrodialysis unit was operated as received
during the entire project, although the stack was dismantled
and cleaned at regular intervals to remove accumulated slime
from the membranes which lowered the removal efficiency.
The unit had some of the same operational procedures as the
reverse osmosis process. The influent was filtered and the
pH adjusted to prevent calcium carbonate precipitation.
Precipitation of calcium sulfate in the brine stream was
prevented by adding dilution water, thus maintaining the
compound within its range of solubility. The blended 3,000
mg/1 TDS influent used for the second membrane stack was
also used to evaluate the electrodialysis unit. The TDS
in this water was reduced by about 23 percent in one pass
through the stack, with a maximum reduction of about 36
percent. Product recovery was about 75 percent of the
influent flow. The unit did not remove the borate ion at
any time but did remove nitrate at an average rate about
twice that calculated for TDS.
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CHAPTER V - PROCESS EVALUATION
This chapter will present an overall evaluation of
the two biological nitrogen removal systems to include removal
levels,, design configuration, and preliminary cost estimates.
Data from the desalination studies will not be included be-
cause neither unit removed nitrogen to the desired level.
Nitrogen Removal
Table 1 summarizes the effluent concentrations
that might be expected from the biological processes studied
at the Treatment Center. The figures for algae stripping
include nitrogen assimilation by the growing algae with sub-
sequent removal of 95 percent of the cells by a harvesting
process.
Table 1
APPROXIMATE EFFLUENT NITROGEN CONCENTRATIONS
EXPECTED FROM THE VARIOUS PROCESSES
STUDIED AT THE IAWTC
Treatment
Process
Approximate Effluent Nitrogen
Concentration in mgN/1*
Summer
N03-N :
Algae Stripping 1.5
Anaerobic Filters 0.5
Covered Anaerobic Ponds
Uncovered Anaerobic Ponds 3.6
Total N
3.0
1.5
2.0
4.7
: Winter
: N03-N :
3.5
0.7
6.0
Total N
4.8
2.0
7.5
*20 mg/1 influent
These data indicate that the anaerobic filter was
the only process studied which provided an effluent of the
desired quality (less than 2 mg/1 total nitrogen). Based
on these data the uncovered anaerobic pond was eliminated
from consideration in the 1970 operational studies.
Process Configuration
Figure 5 shows a schematic diagram of a proposed
algae stripping system. Algal growth is encouraged by the
addition of phosphorus,, iron, and carbon dioxide. The growth
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pond effluent goes through a sedimentation unit, where algae
is coagulated by the addition of ferric sulfate. The slurry
from the sedimentation tank is then dewatered to about 20
percent solids by vacuum filtration. The sludge is then air
or flash dried to about 90 percent solids.
Fe, P, a C02
ADDITION
CHEMICAL
ADDITION
PLANT
INFLUENT
GROWTH
PONDS
SEDIMENTATION
TANKS
PLANT
'EFFLUENT
DEWATERING
MARKETABLE
BYPRODUCT
FIGURE 5--FLOW DIAGRAM OF ALGAL STRIPPING PLANT
Figure 6 shows the proposed configuration for the
two anaerobic processes studied at Firebaugh. The algal
separation facilities, methanol addition, and reaeration are
common to both designs. The sedimentation tank (algal sep-
aration) will probably be necessary to remove suspended
materials coming in from the drainage canal. The decompo-
sition of this material could cause increases in ammonia
and organic nitrogen in the product effluent. Also the sus-
pended material may clog the anaerobic filters. Reaeration
of the effluent will be required to increase the dissolved
oxygen concentration from zero to about 5 mg/1.
The anaerobic filters will include some type of
biomass control system - probably air and water flushing.
The material flushed out will go to a washwater lagoon and
then will be recycled to the head of the plant.
Cost Estimates
The preliminary cost estimates shown in Table 2
were developed for the two biological nitrogen removal pro-
cesses studied at the Treatment Center. The estimates are
for a plant designed to treat an annual flow of 5 x lO^O
million gallons (approximately 1.4 x 1CP acre-feet). April
climatic conditions in the San Joaquin Valley were used to
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i-e2 ^o4
POLYELEC
ADDITK
PLANT T
INFLUENT I *
1
1
L.
POLYELECTR
ADDITIOf
1
PLANT f^
INFLUENT
'3 a
•ROLYTE
DN
, SEDIMENTATION
TANKS
ME™
ADDI
PUMPING
STATION
1
4ANC
TIOI
1 .,
L
PLANT
EFFLUENT
PLANT
EFFLUENT
POND DENITRIFICATION
FIGURE 6-FLOW DIAGRAMS OF BACTERIAL DENITRIFICATION
PLANT-POND AND FILTER CONFIGURATIONS
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predict such important design criteria as depth of pond and
detention time. April was selected as the critical month
because flow and nitrogen levels in a combined tile drainage
collection system are near their predicted yearly maxima.,
while light and temperature remain at relatively low levels.
Table 2
ESTIMATED TREATMENT COSTS FOR REMOVAL
OF NITROGEN FROM SAN JOAQUIN VALLEY TILE DRAINAGE
(Dollars/million gallons)
: Anaerobic Denitrification
Item : Algae Stripping : Pond. : Filter
Capital Cost
O&M
Byproduct Income
114
63
-42
41
47
52
40
Net Cost 135 (45)* 88 (30)* 92 (30)*
•^Approximate cost in dollars per acre-foot
The cost estimates include engineering and contin-
gency factors and were developed to determine which compo-
nents of the various systems were the most costly. With this
information, the 1970 operational studies could be used to
determine methods of reducing the cost of the more expensive
components.
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ACKNOWLEDGMENTS
The nitrogen removal studies at the IAWTC and
the regrowth studies were conducted under the joint
direction of Messrs. Donald G. Swain, Sanitary Engineer,
U. S. Bureau of Reclamation; Percy P. St„ Amant, Jr.,
Sanitary Engineer, Environmental Protection Agency; and
Louis A. Beck., Sanitary Engineer,, California Department
of Water Resources.
Direction of the algae study in the field was
the responsibility of Randall L. Brown (DWR), Bruce A.
Butterfield (DWR), and Joel C. Goldman (DWR), and James
A. Arthur (EPA). Desalination and bacterial denitrifica-
tion were the responsibility of Bryan R. Sword.
The cooperation and assistance given by the
interagency staff of the treatment center was a major
contribution to the success of the field studies. These
personnel were:
James R. Jones . Engineer, U. S. Bureau of Reclamation
William R. Lewis . . Chemist, California Department of
Water Resources
Robert G. Seals Chemist, Environmental
Protection Agency
Norman W. Cederquist . . . Technician, U. S. Bureau of
Reclamation
Gary E. Keller Technician, U. S. Bureau of
Reclamation
Dennis L. Salisbury . Technician, California Department
of Water Resources
Elizabeth J. Boone . Laboratory Aid, California Depart--
ment of Water Resources
Clara P. Hatcher . . Laboratory Aid, California Depart-
ment of Water Resources
William L. Baxter . Laborer, California Department of
Water Resources
Consultants to the Project were:
Dr. William J. Oswald .... University of California
Dr. Clarence G. Golueke . . . University of California
Dr. Perry L. McCarty Stanford University
Report Prepared by:
Randall L. Brown California Department of
Water Resources
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LIST OF REFERENCES
1. Brown, Randall L. 1971. Removal of Nitrate by an Algal
System. California Department of Water Resources Bulletin
No. 174-10, EPA No. 13030 ELY 4/71-7. USER No. REC-R2-71-7-
2. Federal Water Pollution Control Administration. 1967.
Effects of the San Joaquin Master Drain on Water Quality
of the San Francisco Bay and Delta.
3. Sword, Bryan R. 1971a. Denitrification by Anaerobic
Filters and Ponds. Water Quality Office, Environmental
Protection Agency No. 13030 UBH 4/71-8, USER No. REC-R2-
71-8, California Department of Water Resources Bulletin
No. 174-11.
4. Sword, Bryan R. 1971b. Desalination of Agricultural Tile
Drainage. Water Quality Office, Environmental Protection
Agency No. 13030 UBH 5/71-12, USER No. REC-R2-71-12,
California Department of Water Resources Bulletin No. 174-15
5- Tunzi, Milton C. 1971. The Effects of Agricultural
Wastewater Treatment on Algal Bioassay Response. Water
Quality Office, Environmental Protection Agency No. 13030
ELY 9/71-9, USER No. REC-R2-71-9, California Department
of Water Resources Bulletin No. 174-12.
6. Williford, John W. and D. R. Garden. 1971. Techniques to
Reduce Nitrogen Concentration of Drainage Effluent During
Transport or Storage. U. S. Bureau of Reclamation No.
REC-R2-71-10, California Department of Water Resources
Bulletin No. 174-13, EPA No. 13030 ELY 2/71-10.
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PUBLICATIONS
SAN JOAQUIN PROJECT, FIREBAUGH, CALIFORNIA
1968
"is Treatment of Agricultural ¥aste Water Possible?"
Louis A. Beck and Percy P. St. Amant, Jr. Presented
at Fourth International Water Quality Symposium,, San
Francisco,, California., August 14, 1968; published in
the proceedings of the meeting.
1969
"Biological Denitrification of Waste-waters by Addition of
Organic Materials"
Perry L. McCarty, Louis A. Beck, and Percy P.
St. Amant, Jr. Presented at the 24th Annual
Purdue Industrial Waste Conference, Purdue Uni-
versity, Lafayette, Indiana. May 6, 1969.
"Comparison of Nitrate Removal Methods"
Louis A. Beck, Percy P. St. Amant, Jr., and Thomas A.
Tamblyn. Presented at Water Pollution Control Federa-
tion Meeting, Dallas, Texas. October 9, 1969.
"Effect of Surf ace /Volume Relationship, C02 Addition, Aera
tion, and Mixing on Nitrate Utilization by Scenedesmus
Cultures in Subsurface Agricultural Waste Waters"
Randall L. Brown and James F. Arthur. Proceedings
of the Eutrophication-Biostimulation Assessment
Workshop, Berkeley, California, June 19-21, 1969.
"Nitrate Removal Studies at the Interagency Agricultural
Waste Water Treatment Center, Firebaugh, California"
Percy P. St. Amant, Jr., and Louis A. Beck. Presented
at 1969 Conference, California Water Pollution Control
Association, Anaheim, California, and published in the
proceedings of the meeting. May 9^
"Research on Methods of Removing Excess Plant Nutrients from
Water"
Percy P. St. Amant, Jr., and Louis A. Beck.
Presented at 158th National Meeting and Chemical
Exposition, American Chemical Society, New York,
New York. September 8, 1969.
"The Anaerobic Filter for the Denitrification of Agricultural
Subsurface Drainage"
T. A. Tamblyn and B. R. Sword. Presented at the 24th
Purdue Industrial Waste Conference, Lafayette, Indiana.
May 5-8, 1969.
-29-
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PUBLICATIONS (Continued)
1969
"Nutrients in Agricultural Tile Drainage"
W. H. Pierce, L. A. Beck and L. R. Glandon. Presented
at the 1969 Winter Meeting of the American Society of
Agricultural Engineers, Chicago, Illinois.
December 9-12, 1969.
"Treatment of High Nitrate Waters"
Percy P. St. Amant, Jr., and Perry L. McCarty.
Presented at Annual Conference, American Water Works
Association, San Diego, California. May 21, 1969.
American Water Works Association Journal. Vol. 6l.
No". 12. December 1969. pp. o59-bb2.
The following papers were presented at the National Fall
Meeting of the American Geophysical Union,, Hydrology Section,
San Francisco, California. December 15-18, 1969. They
are published in Collected Papers Regarding Nitrates in
Agricultural Waste Water.USDI, FWQA, #13030 ELY
December 19b9-
"The Effects of Nitrogen Removal on the Algal Growth
Potential of San Joaquin Valley Agricultural Tile Drainage
Effluents"
Randall L. Brown, Richard C. Bain, Jr. and Milton G.
Tunzi.
"Harvesting of Algae Grown in Agricultural Wastewaters"
Bruce A. Butterfield and James R. Jones.
"Monitoring Nutrients and Pesticides in Subsurface Agricul-
tural Drainage"
Lawrence R. Glandon, Jr., and Louis A. Beck.
"Combined Nutrient Removal and Transport System for Tile
Drainage from the San Joaquin Valley
Joel C. Goldman, James F. Arthur, William J. Oswald,
and Louis A. Beck.
"Desalination of Irrigation Return Waters"
Bryan R. Sword.
"Bacterial Denitrification of Agricultural Tile Drainage"
Thomas A. Tamblyn, Perry L. McCarty and Percy P.
St. Amant.
"Algal Nutrient Responses in Agricultural Wastewater"
James F. Arthur, Randall L. Brown, Bruce A. Butterfield,
Joel C. Goldman.
v U. S. GOVERNMENT PRINTING OFFICE . 1972—484-484/139
-30-
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1
Accession Number
w
2
Subject Field & Group
Q5 D
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
c I Organization
_£J Dept. of Water Resources
San Joaquin District
Fresno, California
Water Quality Office
Environmental Protection Agency
Pacific Southwest Region
San Francisco, California
Title
Removal of Nitrogen from Tile Drainage - A Summary Report
J Q AathorfB)
Brown., Randall L.
16
Project Designation
13030 ELY-Contract
#l4-o6-200-3389A
2J 1 Note
Available from
Department of Water Resources
P. 0. Box 2385
Fresno, California 93723
22
Citation
Agricultural Wastewater Studies
Report No. 13030 ELY 7/71j DWR Bulletin 174-9
Pages 28, Figures 6, Tables 2
Descriptors (Starred First)
^Agricultural Wastes, *Water Pollution Control, Biological
Treatment, Nitrates, Treatment Facilities
25
Identifiers (Starred First)
*Algal Growth and Harvesting, ^Bacterial Denitrification,
Desalination, Nitrogen Removal
Abstract
27 „-„..-— g^.U(^ies £y an interagency group have shown that it is technically feasible to
reduce 20 mg/1 nitrate-nitrogen in agricultural tile drainage to 2-5 mg/1 by either algae
stripping or bacterial denitrification. Conditions necessary for maximum algal growth
included 8- to 12-inch pond depth, addition of small amounts of nutrients (C02, Fe, and P),
up to four hours of daily mixing and detention times of from 5 to 16 days, depending on the
season. The algae were harvested by coagulation-sedimentation followed by vacuum filtration.
Bacterial denitrification was tested in anaerobic deep ponds and filters using methanol as
a carbon source. Required detention times were on the order of 8 to 50 days for covered
ponds (uncovered ponds were not suitable) and 1 to 2 hours for filters. During long-term
operation of the filters periodic flushing was required to remove accumulated bacterial bi
biomass. Preliminary cost estimates were $90 and $135 per million gallons for bacterial
denitrification (either pond or filter) and algae stripping respectively. Laboratory
studies indicated that nitrogen removal effectively lowered the biostimulatory nature of
the waste with respect to algal growth in potential receiving waters.
Two desalination processes were also studied — electrodialysis and reverse osmosis.
Both processes effectively reduced total dissolved solids but neither removed boron, or
reduced nitrate to the desired level.
Abstractor
Brown
Institution
Department
of
Water
Resources
WR:102 (REV. JULY 1969)
WRSI C
SEND. WITH COPY OF DOCUMENT. TO: WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C. 20240
GPO: 1970 - 407 -89
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