EPA RESEARCH ON LAND TREATMENT
by
Richard E. Thomas and Curtis C. Harlin, Jr.
Water Quality Control Branch
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
Prepared for
U.S. Environmental Protection Agency
Technology Transfer Program
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ABSTRACT
The Water Quality Control Branch of the Robert S. Kerr Environmental
Research Laboratory has been assigned EPA responsibility for conduct
of in-house and extramural research on land application of municipal
effluents and the use of effluents in aquaculture projects. We have
integrated our research covering these approaches because the shift
from land application through wetland systems to aquaculture is a
gradual transition and all approaches rely on closely integrated
scientific principles. Although the specific topic of this seminar
focuses on land application, we should remember that combined land
application and aquaculture systems have potential for certain needs.
The major focus of our land application research effort is the development
of a technical data base which will establish the capabilities of land appli-
cation approaches for management of wastewaters. Although the concept
of applying wastewaters to the land has been with us for centuries, the
needs of today and the future pose new questions about the suitability
of the concept for proposed widespread and greatly varied uses. The
objective of this presentation will be to acquaint participants with both
the short-term and long-term plans for accomplishing the research needed
to bolster existing information for implementing land-based wastewater
management systems.
Our research plan has been developed around the thesis that the many
differing approaches for applying wastewater to the land can be
categorized into three groupings. These groupings are identified as
cropland irrigation, infiltration-percolation, and overland flow. This
presentation will summarize information about completed, ongoing, and
planned research of the Water Quality Control Branch.
This summary of completed and ongoing projects will highlight major
research findings which pertain to consideration of practical implemen-
tation of land-based systems now. Emphasis will be placed on research
data which points to factors of prime interest for site selection and
system design when considering land application as a wastewater
management alternative. Research conducted by several EPA divisions
and other sources will be used to supplement that conducted under the
guidance of the Water Quality Control Branch at the Robert S. Kerr
Environmental Research Laboratory.
The coverage of research planned for initiation in FY-1975 and in future
years will address major issues which need further resolution. Emphasis
will be placed on detailing a projected timetable for the accumulation of
reliable data to clarify these major areas needing further resolution. The
elaboration of the long-term research timetable will include detail on the
type of interim data which will be available as well as the projected
long-term goals.
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SECTION I
INTRODUCTION
The Water Quality Control Branch (WQCB) of the Robert S. Kerr Environ-
mental Research Laboratory (RSKERL) has been assigned Environmental
Protection Agency (EPA) responsibility for research to utilize agriculture,
silviculture, or aquaculture projects for management of municipal waste-
waters. The major focus of this integrated research program is the
development of a reliable data base which establishes the capability of
these approaches with respect to National goals for wastewater management.
The transition from strictly land application through wetland systems to
strictly aquaculture systems is a gradual change and all of these systems
are influenced by similar scientific principles. For this reason, this
discussion of land application will cover some concepts which some
people would consider as aquaculture approaches.
Historically, the involvement of the WQCB in research on land application
of municipal wastewaters predates the formation of EPA by many years.
Projects supported by predecessor agencies, including the Federal
Water Quality Administration, the Federal Water Pollution Control
Administration, and the U.S. Public Health Service, are an integral part
of technical data base being developed by the WQCB. The results of
these projects conducted under the auspices of predecessor agencies
provide much of the current data base and serve as the principal guides
for the direction of short-term and long-term research goals.
Short-term needs are designated as those associated with improvements
scheduled for adoption within five years, while the long-term needs are
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designated as those associated with the 1983 and 1985 goals of the Water
Pollution Control Act of 1972. Short-term plans place emphasis on
expanding our quantitative data base through investigation of current
operations involving crop irrigation and infiltration systems. Comple-
mentary research is being conducted to develop innovative approaches
for achieving secondary treatment or more advanced levels of treatment.
One such approach is overland-flow treatment of raw comminuted waste-
water to achieve low cost and advanced treatment without production of
sludge. Long-term plans provide more flexibility for evaluation of
integrated systems directed to the attainment of management concepts
to achieve greater reuse of wastewaters. Plans for obtaining this goal
incorporate more laboratory studies and field development studies
directed to modifying existing practices, combining process units to
achieve better reuse of wastewater constituents, and exploring new
ideas for incorporating wastewater reuse into the production of food
and fiber products. One example of such an integrated system is the
combining of overland flow, high-rate infiltration, and a fish rearing
pond in sequence to produce a clear, stable effluent low in nutrients and
bacteriologically acceptable for discharge without further disinfection.
These EPA efforts are coordinated with the efforts of other Federal
agencies through participation in interagency committee work and
through joint support of projects. Extramural projects funded through
contracts, grants, or interagency agreements play a major role in the
improvement and expansion of the data base for planning and designing
land application systems. Our principal purpose at this seminar is to
highlight research activities which may influence design and management
of land application systems which you, as system planners or system
designers, will be considering in the near future.
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SECTION II
ONGOING RESEARCH
First, let us address some completed or ongoing studies in detail to
assess plans for filling the gaps in the technological data base. Detailed
discussion of the results of completed or ongoing studies will be directed
to clarification of technical judgments regarding the present technical
data base. Discussion of future plans will provide insight into the types
of additional short-term information being sought and an estimate of when
various bits of information will become available.
COMPLETED AND ONGOING STUDIES
This discussion will address crop irrigation, infiltration-percolation,
and overland-flow projects separately. An additional category of basic
research applicable to more than one category will close the section.
Crop Irrigation
Cropland irrigation with municipal effluents is a well-established practice
in the southwestern United States. Many facilities have practiced effluent
irrigation for more than 30 years at the same site. Utilization of the prac-
tice has grown steadily since the first operations were initiated in the
late 1800's and some 300 facilities are active at present. In spite of this
number of active facilities, there is an obvious lack of quantitative data
to delineate the balance between the beneficial and adverse influences
on the local environment. Our laboratory has completed or is actively
involved in ten field projects addressing various aspects of crop
irrigation practices.
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One group of projects places emphasis on locating and evaluating
currently available quantitative information on application rates, crop
responses, soil changes, and groundwater quality changes. To date,
this approach has been very useful in defining management techniques
for general use in the Southwest, as well as furnishing a base for other
geographic locations. A recently completed survey of existing facilities
and an assessment of current technology summarize the accomplishments.
A second group of projects is designed to demonstrate crop irrigation
approaches in geographic areas where historical information is scarce.
The long-term project at Pennsylvania State University is an example
of a project of specific regional significance. The ten years of data
collection at this site shows that crop irrigation can benefit crop produc-
tion in a cool, humid climate with little effect on the local groundwater
body. Other ongoing demonstration projects of specific interest include
the Muskegon Wastewater Management System; a smaller study at Belding,
Michigan; a study atFalmouth, Massachusetts; and a study at Tallahassee,
Florida. Some of these projects will be covered in detail by other speakers
so comments on individual projects will be brief. The Muskegon project
is designed to demonstrate seasonal irrigation in conjunction with off-
season storage of all treated wastewater, as well as complete recovery
of the renovated wastewater for surface discharge. This total contain-
ment system represents a very advanced concept of crop irrigation for
wastewater management. The 1975 season will be the first for collection
of full season data for all system components. Data collected over the next
several years will be an important addition to the current data base. The
study at Belding, Michigan utilizes an oxidation pond effluent (a 5-cell
pond system) in a summer irrigation program for forages, sod, and
ornamentals, and in a winter irrigation program for forages. This study
is providing additional data on winter operations, responses of sod and
ornamentals, and water quality influences resulting from non-containment
operations. The site has sandy soils over a shallow water table which
promotes lateral movement through interflow with discharge to a surface
stream. The Falmouth, Massachusetts study is designed to demonstrate
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several management techniques on sandy soils with recharge of the
groundwater in a sand aquifer at a depth of about ten meters. The
Tallahassee, Florida study has a similar objective for a project site with
radically differing climatic conditions. Interpretative data from these
projects will become available within a year or two.
Infiltration-Percolation
Infiltration-percolation is a well established practice at many small
municipal facilities throughout the United States. Design and operation
of these systems have emphasized disposal of a treatment plant effluent,
and it is only within the last decade that an effort has been made to
determine the treatment which can be achieved by adjusting the manage-
ment of a system. Our laboratory has been or is actively involved in
nine field studies addressing the evaluation and demonstration
of management options which enhance the treatment achieved by
infiltration-percolation systems.
Previously completed studies include four research studies in water-
short southwestern states and two research studies in water-rich north
central states. The studies in the southwest were conducted at Whittier
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Narrows, California, Santee, California, Phoenix, Arizona, and
Hemet, California. The studies in the north central area were in
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Detroit Lakes, Minnesota, and Westby, Wisconsin. The study at
Whittier Narrows, California was conducted to study the effectiveness
of the infiltration-approach for direct recharge of a potable groundwater
A
supply with secondary effluent. The results of this study showed that
spreading periods of about 9 hours followed by drying periods of about
15 hours produced a clear and highly oxidized water acceptable for
recharge at this site. This method of operation resulted in conversion
of almost all applied nitrogen to nitrate and produced nitrate concentra-
tions of 20 to 30 mg/1 in the renovated water. Since these concentrations
exceeded the 10 mg/1 limit for drinking water, it was recommended that
dilution with low nitrate water would be necessary before repumping
for use as a water supply. The concurrent study at Santee, California
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evaluated the use of infiltration-percolation to make municipal effluent
suitable to fill and maintain the water level in recreational lakes.
Locating the infiltration-percolation basins in the alluvium of a shallow
stream channel provided substantial lateral movement underground
after about 3 meters of vertical percolation. In addition to excellent
removal of solids, oxygen-demanding substances, pathogens, and
phosphorus, total nitrogen in the renovated water was reduced to
1.5 mg/1 (from 25 mg/1 applied to spreading basins) after about 500
meters of lateral underground travel. Emphasis was placed on evaluating
this nitrogen removal at the Phoenix, Arizona study using a similar mode
of operation. Results of the Phoenix study showed that the frequency
of application has a major influence on nitrogen removal. Spreading and
drying periods of a few days or less promoted nitrification and resulted
in less than 10% total nitrogen removal, whereas spreading and drying
periods of 10 to 20 days resulted in apparent denitnfication and up to
80% nitrogen removal. In the third year of study it was shown that this
degree of removal was a combination of adsorption and denitnfication .
This study also highlighted the importance of underground residence
time and/or distance of travel for achieving phosphorus removal at the
high loadings used for the infiltration-percolation approach.
Another important factor related to local hydrological conditions was
graphically demonstrated by the study at Hemet, California. An un-
usually wet winter season at this location caused the local water table
to rise up to the bottom of the spreading basins. The resultant reduction
in hydraulic acceptance rate and deterioration of treatment efficiency
made it necessary to quickly develop an alternate method for handling
their effluent.
Although the two north central area studies represent radically differing
climatic conditions, overall performance was quite similar to that observed
in the southwest. The Detroit Lakes, Minnesota project entailed a four-
year experiment using 20-hour spraying periods followed by 4-hour
drying periods to apply about 30 meters per year of effluent on a sandy
soil.8 Our definitions place this system in the infiltration-percolation
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category even though it used sprinkler application and is referred to as
a spray irrigation system. It is significant that the use of short spreading
and drying cycles in this climate produced nitrogen and phosphorus
interactions comparable to those for studies in the southwest. Nitrogen
was converted to nitrate which appeared in the groundwater (at a
concentration comparable to that in a municipal effluent) while 70% of
the phosphorus was removed after no more than 7 meters of travel
distance through the soil. The other study in this climate was a one-year
o
evaluation of the performance of an existing ridge and furrow basin facility.
The system was located on a silt loam soil and a loading of about 15 meters
per year was obtained with wetting periods of two weeks followed by
drying periods of two weeks. As was the case for the study in Arizona,
the long spreading period resulted in about 70% removal of total nitrogen
without affecting the removal capacity for other measured parameters.
The first of several studies to make comprehensive evaluations of existing
infiltration-percolation facilities has just been initiated at Lake George,
New York. Results of previous studies at this site show that the
35-year-old infiltration system at this site has good potential for further
collection of quantitative data. Several studies of this type will be
implemented to expand the scope of quantitative data to include parameters
of current interest. Completed and ongoing research on the infiltration-
percolation approach to land spreading of municipal effluents are
encouraging for future use on a much larger scale. Technological data
are already available to design and operate systems for a limited number
of situations, but of more importance is the apparent utility of the
approach under widely differing climatic conditions. We are optimistic
that further research efforts can establish well-defined design criteria
and management techniques for use throughout the United States.
Overland Flow
Overland-flow treatment of municipal wastewaters is a newly developing
technology in the United States. Our laboratory has completed an
18-month study to assess the technical feasibility of treating raw sewage
by overland flow. The positive results of this study, as well as a just
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completed 15-month extension of the study to explore alum addition for
improving phosphorus removal have led to two new studies. One of
these is a field evaluation to study overland flow for a 380 m3 daily flow
(0.1 mgd) at a small rural city. The second is a test to compare treat-
ment efficiency and area requirements for primary and secondary effluents
as opposed to direct treatment of raw sewage. These efforts are the initial
steps in a broader effort which will be required to establish a sound data
base for implementation of overland flow as a ready alternative to other
established wastewater management approaches.
Basic Research
In addition to studies addressing specific land application approaches,
our laboratory is conducting or has supported several studies on funda-
mental processes which are involved in the functioning of land application
systems. Studies have been focused on special aspects of phosphorus
retention in soils, denitrification, biodegradation of organics, and
climatology.
Phosphorus retention in soil has been studied from the specific aspect
of predicting long-term phosphorus removals by measurement of specified
soil properties . Enfield has reported an initial prediction model based
on laboratory work with 26 mineral soils. Completed and ongoing denitri-
fication studies are addressing the relation of oxygen status in an attempt
to delineate management approaches for achieving and maintaining 90%
nitrogen removal by denitrification. Continuing studies on biodegra-
dation of organics have addressed the use of ATP (adenosine triphosphate)
as a tool to measure bioactivity and the use of small-scale laboratory
apparatus to assess the relative biodegradability of wastewaters from
different sources. The study of climatology has been directed to assessing
methodology to use readily available weather data for determining winter
storage needs. These basic studies have applicability to all three land
application approaches and provide a better basis for establishing field
projects to develop or demonstrate specific features of improved
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technology. Details on these projects shall not be given because the
primary focus of this seminar is on information which can be used now
rather than what may happen as a result of present research activities.
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SECTION III
FUTURE RESEARCH
Future plans for research on land application approaches adhere to our
categorization of land application into three specific types of systems.
As indicated, short-term plans call for utilization of studies on existing
systems and selected demonstration projects to gain as much improvement
in the data base as is possible in a short time. These short-term plans
address the 1977 and to some degree the 1983 milestone dates of PL 92-500.
The long-term plans call for directing more attention to the study of
innovative combinations of land application alone or with other process
units to achieve a very high degree of contaminant control. These long-
term plans address the 1985 goal of non-polluting discharge, as well as
the intermediate 1983 goal of best practicable waste treatment technology.
SHORT-TERM PLANS
Projected Branch support over the next two to three years will provide a
diversified program which will make important gains in all four of the
major research areas. Emphasis will be placed on filling technology gaps
for the crop irrigation and infiltration-percolation approaches which are
being implemented as alternative wastewater management systems at the
present time. Development of overland-flow technology will be aimed at
assisting small rural communities needing a simple and economical
secondary process. Basic research will continue with little change in
goals or emphasis.
A major fraction of short-term support will be allocated to collection of
quantitative data at about ten existing crop irrigation systems and ten
existing infiltration-percolation systems. These one- to two-year
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studies should be completed by the end of FY-1977 and the results of
the studies will be distributed as technical information bulletins shortly
thereafter. The short-term plans also call for initiation of several
demonstration projects in anticipation of a need to demonstrate improved
management techniques for the crop irrigation and infiltration-percolation
systems. Efforts will be made to select project sites in geographic locales
where governmental units and the public are interested in the potential
of land application but do not have ready access to observe an ongoing
facility. These short-term efforts on the crop irrigation and infiltration
approaches will emphasize the collection of quantitative data to delineate
the capabilities of existing design technology. Major efforts to develop
new design technology will be considered as a long-term objective.
The short-term plans for overland-flow studies address the development
of new technology. Short-term objectives for overland-flow studies will
emphasize two areas of development. One of these will be the development
of overland flow as a unit process for treatment of raw municipal waste-
waters on a year-round basis in warm climates. Overland flow will offer
many rural communities a much needed method for meeting or exceeding
the present definition of secondary treatment at a cost comparable to that
of primary treatment. The second objective will be the development of
overland flow as a seasonal operation for upgrading existing pond systems
which cannot meet present criteria for secondary treatment. The prospects
for developing a timely data base for these two objectives are good and
there is an obvious need for the intended results.
Basic research will continue in the areas already under study, as well
as being expanded to include work on heavy metals. Short-term goals
include positive identification of denitrification as the mechanism for
nitrogen removal by overland flow; establishment of a method for pre-
dicting soil removal of phosphorus; a routine methodology for predicting
winter storage needs from weather station data; and development of the
ATP procedure for measuring bioactivity in soils. Completion of work
in other areas will fall under long-term plans.
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LONG-TERM PLANS
Projected Branch support from FY-1977 through FY-1981 should support
a program which will culminate in the distribution of additional technical
bulletins on crop irrigation, infiltration-percolation, and overland flow
to supplement EPA Technical Bulletin EPA-430/9-75-001. These technical
bulletins will detail improved procedures for planning a land-based
wastewater management system, selecting the process tram best suited
to the site, designing the system, and operating the system. These
technical bulletins will be complemented by a series of research reports
providing reliable technical data which substantiate the recommendations
contained in the bulletins. Much of the data in the research reports will
have come from demonstration projects which will still be in operation as
permanent facilities. Establishment of demonstration projects at sites
where operations will continue for several decades is a key objective in
long-term plans. The value of these sites for visual inspection and
periodic collection of quantitative data is an essential building block
for establishing a reliable data base which can be extended beyond the
immediate needs for revamping our wastewater management methodology.
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SECTION IV
REFERENCES
Sullivan, Richard H. , Morris M. Cohn, and Samuel S. Baxter.
Survey of Facilities Using Land Application of Wastewater.
Environmental Protection Agency, Washington, B.C. Report
No. EPA-430/9-73-006. July 1973. 377pp.
Pound, Charles E. , and Ronald W. Crites. Wastewater Treatment
and Reuse by Land Application--Vol. II. Environmental Protection
Agency, Washington, D.C. Report No. EPA-660/2-73-006b.
August 1973. 249 pp.
Kardos, Louis T., William E. Sopper, Earl A. Myers, Richard R.
Parizek, and John B. Nesbitt. Renovation of Secondary Effluent
for Reuse as a Water Resource. Environmental Protection Agency,
Washington, D.C. Report No. EPA-660/2-74-016. February 1974.
495pp.
McMichael, Francis Clay, and Jack Edward McKee. Wastewater
Reclamation at Whittier Narrows. The Resources Agency, State
Water Quality Control Board, Sacramento, California. Publication
No. 33. 1966. 100 pp.
Merrell, John C. , Jr. , Albert Katko, and Herbert E. Pintler.
The Santee Recreation Project, Santee, California (Summary
Report) . Public Health Service Publication No. 99-VP-27.
December 1965. 69pp.
Bouwer, Herman, R. C. Rice, E. D. Escarcega, and M.S. Riggs.
Renovating Secondary Sewage by Ground Water Recharge with
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Infiltration Basins. Environmental Protection Agency, Washington,
B.C. Report No. 16060 DRV 03/72. March 1972. 102 pp.
7. Eastern Municipal Water District. Study of Reutilization of
Wastewater Recycled Through Ground Water . Environmental
Protection Agency, Washington, D.C. Water Pollut. Contr.
Research Report Series No. 16060DDZ07/71. Vol. 1. July 1971.
8. Larson, Winston C. Spray Irrigation for the Removal of Nutrients
in Sewage Treatment Plant Effluent as Practiced at Detroit Lakes,
Minnesota. In: Algae and Metropolitan Wastes, Transactions of
the 1960 Seminar. U.S. Dept. of Health, Education and Welfare.
pp. 125-129.
9. Bendixen, Thomas W. , et al. Ridge and Furrow Liquid Waste
Disposal in a Northern Latitude. J. Sanit. Eng . Div. , Proc .
Am . Soc . Civil Eng . 94(SA1): 147-157. February 1968.
10. Aulenbach, Donald B., James J. Ferris, Nicholas L. Clesceri, and
T. James Tofflemire. Thirty-five Years of Use of a Natural Sand
Bed for Polishing a Secondary Treated Effluent. (Presented at
Rural Environmental Engineering Conference. University of
Vermont. September 27, 1973.) 46pp.
11. Thomas, R. E., K. Jackson, and L. Penrod. Feasibility of
Overland Flow for Treatment of Raw Domestic Wastewater .
Environmental Protection Agency, Corvallis, Oregon. Report
No. EPA-660/2-74-087. December 1974. 30pp.
12. Enfield, C. G., and D. C. Shew. Comparison of Two Predictive
Non-Equilibrium One-Dimensional Models for Phosphorus Sorption
and Movement Through Homogeneous Soils. J. Environ. Quality.
Vol. 4, No. 1. January-March 1975.
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