EPA600/2-78-110
x>EPA
Municipal
Wastewater
Aquaculture
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U S Environmental
Protection Agency, have been grouped into nine series These nine broad cate-
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This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution This work
provides the new or improved technology required for the control and treatment
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This document is available to the public through the National Technical Informa-
tion Service, Springfield. Virginia 22161
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EPA-600/2-78-110
June 1978
MUNICIPAL WASTEWATER AQUACULTURE
by
William R. Duffer and James E. Moyer
Wastewater Management Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
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DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publication.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
ii
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FOREWORD
The Environmental Protection Agency was established to coordinate
administration of the major Federal programs designed to protect the
quality of our environment.
An important part of the agency's effort involves the search for
information about environmental problems, management techniques and new
technologies through which optimum use of the nation's land and water
resources can be assured and the threat pollution poses to the welfare
of the American people can be minimized.
EPA's Office of Research and Development conducts this search
through a nationwide network of research facilities.
As one of these facilities, the Robert S. Kerr Environmental
Research Laboratory is responsible for the management of programs to:
(a) investigate the nature, transport, fate and management of pollutants
in groundwater; (b) develop and demonstrate methods for treating waste-
waters with soil and other natural systems; (c) develop and demonstrate
pollution control technologies for irrigation return flows; (d) develop
and demonstrate pollution control technologies for animal production
wastes; (e) develop and demonstrate technologies to prevent, control or
abate pollution from the petroleum refining and petrochemical indus-
tries; and (f) develop and demonstrate technologies to manage pollution
resulting from combinations of industrial wastewaters or industrial/
municipal wastewaters.
This report contributes to the knowledge essential if the EPA is to
meet the requirements of environmental laws that it establish and enforce
pollution control standards which are reasonable, cost effective and
provide adequate protection for the American public.
William C. Galegar
Director
Robert S. Kerr Environmental Research Laboratory
iii
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ABSTRACT
The developmental status of the aquacultural alternative for treatment and
reuse of municipal wastewater is reviewed. Major emphasis is given to the reduc-
tion or fate of pollutants in such areas as organics, solids, nutrients, heavy
metals, residual hydrocarbons, and potentially pathogenic organisms. Economic
assessments of treatment and production rates for organisms are included for
several types of aquacultural processes. Aquacultural systems considered include
natural wetlands, artificial wetlands, macrophytes, invertebrates, fish, and
integrated or food chain units. The literature examined indicates that information
available at this time is not adequate for design of operational aquaculture systems
to treat or utilize inputs of municipal wastewater. Sufficient exploratory studies
have been conducted, however, to demonstrate a definite potential for development
of wastewater aquaculture systems. Areas having high potential for further
research and development are identified. This report covers recent research
progress in municipal wastewater aquaculture and was completed as of June 1977.
IV
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CONTENTS
Foreword ill
Abstract iv
Tables vi
1. Introduction 1
2. Conclusions 2
3. Recommendations 4
4. Literature Survey 6
Natural Wetlands 6
Artificial Wetlands 9
Macrophytes 12
Invertebrates 15
Fish i 17
Integrated Systems 18
Economic Evaluation 21
5. Evaluation of Research Progress 38
References 41
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TABLES
Number
1 Performance and Costs of Hyacinth Tertiary Treatment Systems 24
2 Performance and Costs of Competitive Tertiary Treatment
Systems 25
3 Estimated Costs of Treatment by Strategy and State 26
4 Estimated Fish Output from the Various Aquaculture Strategies 33
5 Estimated Annual Net Revenues from Aquaculture 34
6 Cumulative Percent Reduction of Pollutants, by Strategy and
State 35
7 Cost Effective Comparison of Systems to Achieve Alternative
Levels of BOD 5 and Suspended Solids 36
8 Cost Effective Comparison of Systems to Achieve Alternative
Objective Levels of Phosphorus and TKN 37
9 Reductions of Selected Parameters by Aquaculture Systems 40
VI
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SECTION 1
INTRODUCTION
Environmental problems associated with the disposal of wastewater are
prompting the development of economical and reasonable treatment and reuse
approaches in order to minimize the unnecessary expenditure of tax dollars and
energy. The Federal Water Pollution Control Act of 1972 [PL 92-500 § 201 (d)
(1) ] requires that agricultural, aquacultural and silvicultural alternatives for
wastewater reuse be evaluated and encouraged as treatment mechanisms.
The purpose of this report is to review the developmental status of the aquacul-
tural alternative for treatment and reuse of municipal wastewater. Aquaculture
is defined as the production of aquatic organisms under controlled conditions.
The aquatic flora and fauna are included for both marine and freshwater systems.
Although the scope of this review is limited to municipal wastewater inputs
into aquatic systems, aquacultural technology is also developing for industrial
wastewater and non-wastewater sources. It should be noted that the same basic
biological principles apply to all systems designed for the culture of aquatic
organisms. Such factors as reproductive characteristics , life stage environmental
requirements, feeding habits, and tolerance of high density populations must
be taken into account in order to establish successful culturing procedures.
The major portion of technology developed for aquaculture has been oriented
toward the production of human food items rather than treatment or reuse of
wastewater. Bardach et al. (1) provide an excellent review of the developmental
history, and current world-wide practices in aquaculture, but their consideration
is limited only to those organisms which are cultured as human food.
According to the broad definition selected for aquaculture, conventional
municipal wastewater treatment processes such as trickling filters, activated
sludge, and sewage oxidation ponds could be included for review. We have,
however, limited the scope to include only new or developmental processes rather
than conventional or advanced application processes. For example, the aquacultur-
al application which utilizes planktonic algae in combination with aerobic bacteria
to oxidize organic wastes in sewage oxidation ponds is not included. Culture
of higher food chain organisms, such as aquatic invertebrates and fish which
feed either directly or indirectly on unicellular forms, however, is included.
Higher aquatic plants will also be considered since their culture is in the develop -
mental phase. For natural systems, such as marshes and wetlands, the treatment
effects of the overall population is examined with no distinction of the various
food chain components.
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SECTION 2
CONCLUSIONS
Aquaculture has been practiced for centuries in various parts of the world,
and has been a significant source of food and fiber production in some countries.
The application of waste materials to producing aquaculture systems for their
fertilizer value has been a common practice through the years in some parts
of the world. Only recently, however, has the use of designed aquaculture systems
for treatment and management of municipal wastewaters been given serious consider-
ation .
With the growing interest in aquaculture utilizing municipal wastewaters,
there has been an increase in research activities in this area. This review of
the current literature indicates that several different systems have been studied.
These studies lack uniformity of approach and purpose; therefore, results are
not easily compared and sometimes are conflicting or inconclusive.
Although there are many unanswered questions at this time regarding the
use of designed aquaculture systems for municipal wastewater treatment and
reuse, there are growing numbers of researchers, planners, and managers who
believe that aquaculture has potential for development as an economical, simple,
and effective alternative for municipal wastewater treatment and management.
In addition, it is felt that, while offering an effective treatment alternative, aquacul-
ture can yield a product of economic value to defray part of the operating costs.
Another attractive feature is the potential energy savings of aquaculture wastewater
treatment as compared to alternative systems. There are indications that some
systems can, indeed, be energy producers by the conversion of a crop, such
as water hyacinths, to a valuable fuel.
The overall conclusion of this study is that developmental research in municipal
wastewater aquaculture is needed in order to establish reliable design criteria.
Investigations to date indicate that the culture of several types of aquatic organisms
have potential for development as an attractive alternative to conventional wastewater
treatment systems from from the standpoints of both treatment effectiveness and
economic feasibility. The following specific conclusions are offered to support
the overall conclusion:
1. Exploratory efforts with the culture of water hyacinths for treatment
of municipal wastewater has progressed more rapidly than those utilizing other
organisms. Although the use of water hyacinths is limited geographically, research
progress warrants a significant developmental effort oriented toward establishing
design criteria.
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2. Aquatic plants which are cosmopolitan under natural environmental condi-
tions appear to have greater potential for wastewater treatment than those restricted
in distribution due to temperature tolerance or other factors.
3. Wetland systems which could be established over a wide geographical
area for freshwater and brackish water have great potential for developmental
research in areas of wastewater treatment and utilization.
4. A large portion of research activity in aquaculture utilizing municipal
wastewaters has emphasized production of organisms rather than treatment of
wastewater. Research must be conducted to develop system design criteria related
to process stability, costs and revenues, and treatment effectiveness.
5. Only a limited number of available organisms have been cultured experi-
mentally using municipal wastewater. Of those studied, water hyacinth, seaweed,
and midge larvae have demonstrated an impressive potential for production under
conditions of wastewater culture .
6. Few exploratory tests have been conducted with supplemental feeding
of aquatic animals or supplemental fertilizing of aquatic plants in municipal waste-
water culture systems. Recycling of municipal wastewater utilizing supplementation
should be investigated in order to determine the developmental potential for such
practices.
7. Freshwater systems have a distinct advantage over marine systems for
municipal wastewater treatment application. The advantage is due to the require-
ment for a much smaller volume of water which would result in a saving of equipment
and/or space. Since wastewater effluents from municipal sources are more similar
to freshwater than seawater, freshwater organisms may be cultured using non-
diluted effluents, whereas marine systems require extensive seawater dilutions
in order to maintain a favorable salinity range for the culture organisms.
8. Potential problems in the areas of disease transmission, health effects,
and social acceptance pose a significant barrier to utilization of municipal wastewater
products as food for humans. Developmental research for the present should
concentrate on other product uses for organisms cultured in municipal wastewater.
9. Existing studies indicate that wastewater treatment by aquaculture may
have its best application in combination with other methods of treatment. While
revenues from the sale of aquacultural products may return a portion of the total
construction and operation costs of such combined systems, income from product
sales is usually insignificant compared to the overall expense of the system.
In some cases, however, if comparisons of revenues and expenses are restricted
only to the aquacultural component, a substantial net return for this component
may be realized while providing additional wastewater treatment.
10. Reported water quality changes resulting from aquaculture systems vary
widely with respect to type of system and mode of operation. Not considering
differences in operation or other factors which would influence results, there
is a wide variation in reporting of parameters for the same general type system.
Probably more significant to this study are the serious omissions in data, lack
of consistency in reporting, and comparability of information among the various
researchers.
3
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SECTION 3
RECOMMENDATIONS
Results of this review clearly indicate that man can recycle and treat waste-
water by culturing aquatic organisms to simulate a portion of nature's activity. In
this process, changes occur in the chemical, physical, and biological characteristics
of the system. Unregulated changes are often detrimental to the system affecting
such factors as survival, reproduction, and rates of growth. In those instances,
however, where techniques have been developed for controlling inputs of food sub-
stances and nutrients and for regulating other critical environmental variables,
an enriched aquatic system having high rates of production can be achieved. Muni-
cipal wastewaters contain highly valuable nutrient materials and are subject to
management as aquatic systems for increased productivity.
Recommendations are oriented toward identifying appropriate culture organisms
and developing the techniques required for regulating aquatic systems which receive
inputs of municipal wastewater for purposes of treatment or recycling. The specific
recommendations which follow are listed in priority order based on our opinion of
the status of technological progress, present potential for research development of
design criteria, and the exploratory effort needed to provide a technical base for
future developmental research.
1. Additional developmental research with water hyacinth should be con-
ducted to establish process design criteria for its natural geographical
and climatic boundaries.
2. Consistent and uniform evaluation parameters should be adopted to allow
comparison of results for different aquaculture systems and from differ-
ent research projects.
3. Pilot-scale facilities with extensive control features should be utilized
in developmental experiments to assure the research flexibility necessary
for determining environmental tolerances, production rates, and changes
in water quality associated with populations of test organisms.
4. Experiments with water hyacinth in a controlled environment should be
conducted in order to evaluate extending the geographical and climatic
areas of potential utilization.
5. Exploratory research should be conducted to determine the potential of
aquatic macrophytes such as cattails, waterweeds, duckweeds, and
bullrushes for utilization in development of municipal wastewater treat-
ment processes.
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6. Research should be conducted on utilization of artificial wetlands for
wastewater treatment. Techniques for establishing and maintaining
such areas, as well as wastewater pretreatment requirements and load-
ing rates, should be determined.
7. Research to determine the value of natural wetlands systems for utilization
of municipal wastewater should be expanded. Beneficial and detrimental
effects of wastewater inputs must be determined in order to fully protect
these systems.
8. Additional experiments should be conducted with organisms such as sea-
weed, midge larvae, and certain finfish species which have demonstrated
a potential for increased production under conditions of wastewater cul-
ture.
9. Research into health effects associated with wastewater aquaculture
should be pursued concurrently with research to develop treatment
technology. Public acceptance of wastewater aquaculture will depend to
a great extent on the proven safety, from a public health standpoint, of
these systems . Delays in the implementation of aquaculture systems,
shown to be technically feasible, can be largely avoided by early identi-
fication and resolution of health-related problems.
10. Studies to fully develop the economics of wastewater aquaculture should
be conducted. Reliable cost data must be developed for construction,
operation, and maintenance. These data should be correlated with treat-
ment efficiencies in order that reliable cost effectiveness analyses may
be performed, and fair comparisons made with other treatment alternatives.
Data should be developed for revenues and other tangible benefits which
could be produced from wastewater aquaculture.
11. As design criteria are developed for municipal wastewater aquaculture
processes, research efforts should include a complete evaluation of energy
requirements related to treatment efficiencies in order to allow a valid
comparison with other types of systems. It appears that many wastewater
aquaculture systems will offer significant energy savings due to effici-
encies achieved by direct conversion of solar energy by aquatic plants.
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SECTION 4
LITERATURE SURVEY
The literature search for this report has been limited to those aquacultural
studies concerned with the treatment and reuse of municipal wastewaters; moreover,
it has been confined primarily to those investigations of a current and more recent
nature. While ancillary data, such as production rates, have been included
in some instances, major emphasis has been given to the reduction or fate of
pollutants in the following areas of interest: organics, BOD, COD, and others;
solids; nutrients, principally nitrogen and phosphorus compounds; heavy metals;
residual hydrocarbons, such as petroleum and pesticide wastes; and biologicals,
those bacteria and viruses of a potentially pathogenic nature. Economic assessments
are also reported for some types of aquacultural processes. For purposes of
organization, this section of the report has been arbitrarily divided into categories
to include a consideration of natural wetlands, artificial wetlands, macrophytes,
invertebrates, fish, integrated systems, and economic evaluation .
NATURAL WETLANDS
Wetlands, both marine and freshwater, have inadvertently served man as
natural waste treatment systems for centuries; only in more recent years, however,
have these areas received significant attention as valuable resources for degrading
man's contaminants.
In an excellent review article, Valiela, Vince, and Teal (2) point out that
vegetated wetlands act as invaluable natural sinks for wastes by providing areas
for sedimentation and/or adsorption of particulate matter and a reducing environ.-
ment for the conversion of dissolved heavy metals into insoluble sulfides. Addition-
ally, denitrification is enhanced by the presence of microorganisms in the soil
substrate. Plant species present in wetlands readily assimilate dissolved inorganic
nutrients, principally nitrogen and phosphorus compounds, and convert these
substances into plant tissue, thereby limiting accessibility of the chemicals.
The authors state that the predominating plant species colonizing wetlands
are tolerant to a wide variety of environmental stresses, rapidly colonize open
areas, and possess other adaptive mechanisms that allow them to persist in a
changing chemical environment. This wide diversity of plant species has allowed
wetland vegetation to survive the added stresses of processing waste effluents
up to as yet unspecified limits.
In a study of the Brillion marsh located 15 miles below the sewage treatment
plant outfall for the city of Brillion in Calumet County, Wisconsin, Spangler et al.
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(3) noted a dramatic decrease in BOD5 (80.1%) and a significant decrease in
COD (43.7%). A decrease in suspended solids (29.1%) was accompanied by an
increase in dissolved solids (34.0%) which resulted in a net increase of 8.5%
in total solids.
Of the plant nutrients present in municipal wastewaters and sludges, the
macronutrients, phosphorus and nitrogen, have been studied more extensively
by investigators conducting wetland studies due to the essential nature of these
elements for plant growth.
Valiela et al. (2) found that the addition of phosphate had no effect on the
growth of higher plants in saltwater marshes exposed to tidal flooding. This
lack of response by macrophytes was believed to be due to the presence of large
amounts of previously deposited seawater-borne phosphate in the fine sediments
of the marsh. In the Brillion marsh study (3) mentioned previously, similar
results were noted when a mass balance study of total phosphorus, using esti-
mated streamflow data and average phosphorus concentrations, revealed the
same order of magnitude of phosphorus leaving the marsh as entering it. Har-
vesting proved not to be a practical method for the removal of substantial amounts
of phosphorus, as marshes remove phosphorus in the growing season but release
it at other times.
Since the addition of phosphate showed no effect on the growth of higher
plants in saltwater marshes, Valeila and co-workers (2) have attributed the
growth-enhancing properties of sewage sludge to the presence of nitrogen. Follow-
ing experimental enrichment of a marsh with sewage sludge, two- to threefold
increases in the production of higher plants were obtained. In another study
(4) of a brackish marsh in New Jersey dominated by Phragmites communis, the
investigators determined the amount of nitrogen accumulated by the marsh to be
approximately five times the amount contributed by an upstream sewage treatment
plant, even after years of operation.
Valeila et al. (2) state that the amount of sewage nutrient capable of being
processed through wetland vegetation is far greater than that present in the
standing crop, since the vegetation of a wetland is constantly growing and dying.
Harvesting and analysis of above-ground part plants may not present a true picture
of the extent of nutrient removal from sewage application due to the seasonal
transport of these elements between above-ground and below-ground plant parts;
additionally, leaching by the plants of both nitrogen- and phosphorus-containing
compounds may be of significance.
Another process to be considered in the amount of sewage nutrients that
may be processed by wetlands is denitrification by microorganisms present in
the anoxic layers. By means of this process and storage through growth, algae
and bacteria are able to absorb and dispose of a substantial amount of water-borne
nitrogen.
In a study of a freshwater tidal marsh (Hamiltion marshes) located in the
Delaware River Basin, Whigham and Simpson (5) concluded that the high marsh
areas functioned as sinks for nitrogen and phosphorus during the summer months,
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and then slowly released these elements back to the low marsh areas during the
fall and winter, following plant die-off. Greij (6), studying nitrogen concentra-
tions of the Macatawa River in Michigan below a sewage outfall, found that NO >."
nitrogen levels decreased 41.8% from the main current of the river to just inside
a cattail stand of the marsh.
In regard to metal uptake and release by wetlands, Valeila et al. (2) have
stated that this characteristic is dependent upon a number of factors, including
presence of organic matter, distance from the source, salinity, temperature,
pH, the metal element, and sediment type and size. Heavy metals, especially
lead, zinc, and cadmium, are present in large amounts in sewage sludges and
leachates from sanitary landfills. One study by these investigators of marsh
sediments at increasing distances from a landfill operation revealed that the concen-
trations of lead, zinc, and cadmium were rapidly diminished, the lead being
converted to insoluble sulfides while zinc and cadmium were taken up into the
marsh sediments via adsorption and ion exchange processes. Such results indicate
that wetlands provide good sinks for excess heavy metals; however, the marshes
do not serve as permanent sinks such as those found in deep sedimentary deposits.
The reason is that certain plant species can undergo physiological adaptation
that allow their root systems to penetrate the sediment of the anoxic zone and
assimilate heavy metals . More important than the plant life present in wetlands
for the retention of heavy metals is the organic content of the sediment. The
lead concentration of the more organic sediments was found to be about four times
more than sediments from dredge spoil operations (7) .
Most of the losses of zinc and cadmium from wetlands are believed to be through
routes other than plant decay and dead grass exports since only a small percentage
of these metals is taken up by the vegetation present. Shellfish have been suggested
as a source for the removal of metals from wetlands receiving municipal wastes
containing elevated metal concentrations. It is generally believed, however,
that the largest majority of metals are flushed from marshes by tidal action (2) .
Information regarding the fate of organic hydrocarbons in wetlands is extremely
limited (2) . The presence of fine muds should provide a surface for the adsorption
of hydrocarbon products, such as petroleum and pesticides, due to their relatively
low solubilities in water. One study (2) reported a 105-fold concentration of
chlorinated hydrocarbons on muds as compared to that found in sea water. In
a study (2) conducted of a sanitary landfill, polychlorinated biphenyls in the
-leachate were found to be greatest at the source of contamination and rapidly
diminished thereafter.
Despite relatively,low water solubility, hydrocarbons may leach out into
surrounding waters or be structurally altered by exposure or microbial oxi-
dation. In one study by Krebs et al. (8), a substantial amount of aldrin was
microbially oxidized to dieldrin. Petroleum hydrocarbons are known to be degraded
by weathering, leaving complex residues of organic substances (2). Another
factor to be considered in the degradation of hydrocarbons by wetlands is actual
uptake and metabolism of the compounds by the plants themselves; e.g., Seidel
(9) has isolated and developed a number of plant species that are capable of
cleaving hydrocarbons and metabolizing the end products to amino acids for
incorporation into protein.
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The effect of passage through a moderately saline marsh field on the survival
of enteric indicator microorganisms was studied by Valeila et al. (2) . Their
studies showed that the numbers of total and fecal coliforms were halved by resi-
dence over the marsh during tidal inundation. Spangler et al. (3), in studies
on the Brillion Marsh in Wisconsin, found that the total coliform count of the
wastewater was reduced 86.2% following freshwater marsh treatment.
In another series of investigations designed to utilize natural wetlands for
the recycle of treated municipal wastewaters, researchers from the University
of Florida (10) are discharging secondarily treated effluent into cypress domes
at the rate of one inch per week. Results from the project have indicated the
BOD 5, total nitrogen and total phosphorus levels in the dome surface waters
consistently exceeded standards recommended by the State of Florida for wastes
receiving tertiary treatment. The cypress dome disposal method, however,
has been concluded to be more efficacious from the standpoint of conserving and
improving water quality than other more conventional treatment methods—ground-
water injection, overland spreading, or direct release to marine and freshwater
environments.
Kadlec and Kadlec (11) have conducted similar experimentation involving
the disposal of 100,000 gal/day of secondarily treated sewage effluent to a peat
bog marsh area located in the Houghton Lake Wildlife Research Area of Michigan.
The net effect of two seasons of pumping into a 10-acre sector appear to be insignifi-
cant. According to the investigators, "no adverse effects" on the ecology of the
peat bog have been noted when compared to the control areas.
ARTIFICIAL WETLANDS
As the value of wetlands in processing wastes has become increasingly evident,
attempts have been made by investigators to construct artificial systems that
duplicate those waste treatment functions provided by natural wetlands.
In a study of an experimental ditch planted in rushes (Scirpus lacustris)
and reeds (Phragmites australis), DeJong (12) established that the plants contribu-
ted to sewage purification not only through the incorporation of nutrients into
plant tissue, but also by serving as points of attachment for sewage-purifying
microorganisms. The study was conducted during the summer months at a camping
site in the Netherlands, and the experimental ditch occupied a land area of one
hectare (2.47 acres) at a depth of 0.4 meter. Dramatic decreases in the mean
BOD|° from 257 mg/1 to 11 mg/1 (95.7%) and COD from 530 mg/1 to 70 mg/1 (86.8%)
were recorded following ten days' detention. Small and co-workers (13) in a
study at Brookhaven National Laboratory of a 0.2 acre each marsh/pond system
treated with various blends of pre-aerated raw sewage/septage feed, also noted
significant reductions in the average concentrations of these two parameters
over a thirteen-month study period—BOD5 from 148 mg/1 to 30 mg/1 (79.7%);
COD from 427 mg/1 to 56 mg/1 (86.9%) . Utilizing a series of experimental and
control basins lined with PVC and layers of sand and coarse gravel, Spangler
et al. (3) were able to demonstrate that the basin planted in softstem bulrush
(Scirpus validus) was able to remove 91% of the BOD and 61% of the COD after
only five hours' detention.
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Solids data concerning the various artificial wetlands systems are sparse;
however, the following average solids reductions (mg/1) were reported for the
study (13) conducted at Brookhaven National Laboratory: total solids, 548 to
205 (62.6%); total volatile solids, 305 to 100 (67.2%); suspended solids, 331 to
43 (87.0%); volatile suspended solids, 212 to 34 (84.0%); total dissolved solids,
203 to 164 (19.2%).
The data available concerning the uptake of phosphorus compounds by natural
and artificial wetlands appear somewhat anomalous. As mentioned previously,
Valiela et al. (14) have found that the addition of phosphate to salt marshes exposed
to tidal flooding had no effect on higher plant primary production; however,
when added to experimental salt marsh plots, 91-94% was removed. Similarly,
while studies (3) of the Brillion marsh revealed no overall removal of phosphate,
essentially 100% retention was obtained when phosphate compounds were added
to experimental basins. Other studies of artificial wetlands, notably by DeJong
(12) and Small (13) have shown significant phosphate uptake by these systems.
Whether the failure of natural systems to remove phosphate compounds from waste-
waters is the result of a condition of long-term saturation, or due to the absence
of other necessary growth factors remains a matter of conjecture.
Nitrogen uptake by experimental salt marsh plots has been found to be in
the range of 80-94% by Valiela and co-workers (14) . DeJong (12), utilizing a
pond planted in rushes, obtained over 90% nitrogen removal following ten days'
detention. Sixty percent reduction of total nitrogen was measured by Small
and others (13) in their marsh/pond studies. No major qualitative changes in
predominant plant species were noted over a five-year period by Valiela et al.
(15), despite two- to threefold increases in plant growth following nitrogen fertili-
zation. Teal (16) points out that wetland vegetation does not act as a permanent
sink for nutrients. In studies of artificial salt marshes, approximately 12% of
the added nitrogen could be accounted for in above-ground growth. Following
senescence of the grass sward, it was estimated that 6% of the added nitrogen
was lost as dead organic matter.
Other important biological processes to be considered in the utilization of
nitrogen by wetlands include denitrification and nitrogen fixation by microorganisms.
Following addition of combined nitrogen forms to experimental salt marshes,
a reduction in nitrogen fixation was observed (2,17); the microorganisms preferen-
tially utilized the added combined nitrogen rather than performing the energy-
requiring process of fixation.
The uptake of metals by experimental salt water marsh plots fertilized with
sewage sludge has been studied by Valiela (2) and his associates to determine
the extent that vegetation contributes to metal export. Nearly all the lead added
in sludge fertilizer was retained by the marsh surface sediments, and the lead
content of the marsh grasses increased from 2.3 to 4.8 ppm. The greater abso-
lute loss of lead from the fertilized plots as opposed to the control plots through
tidal export was attributed to the increased lead content and the greater biomass
of grass produced by the fertilized plots (15,16,18) . Only minimal amounts,
2-3%, of the added zinc was lost through the export of dead grass (2); 16% was
believed lost through the export of dissolved zinc compounds .* Cadmium exhibit-
ed an even lesser retention than zinc in the fertilized plots, with 66% leaving
other than by grass export.
10
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In a subsequent report by Valiela and Vince (19) of low marsh and high marsh
experimental saltwater plots in which metals were provided by the addition of
a sewage-sludge based fertilizer, the following percentage reductions were observed
as having been retained by the marsh:
Percentage of Added Metal Retained by Marsh
Metal Low Marsh High Marsh
Copper 60 100
Iron 80 100
Lead 55 100
Manganese 55 60
Nickel 45 65
Zinc 20 45
Cadmium 20 35
Chromium 20 50
While it is obvious that the high marsh experimental plots were more effective
in retaining metals, the authors offer no explanation of this apparent anomaly
except to state that the plots were dominantly populated by different plant species.
Small (13), in the thirteen-month study of the marsh/pond system conducted
at Brookhaven National Laboratory, reported the following average metal reduc-
tions between the sewage influent and effluent water of the system: chromium-
80%, copper-96%, iron-68%, manganese-97%, and zinc-86%. While initial concentra-
tions of these metals were not overly high, it is obvious that the marsh/ pond
system was extremely effective in removing metals from sewage wastewaters.
An additional factor to be considered in the removal of metals from waste-
waters by plants is the plant's ability to adapt to growth in the presence of greatly
increased concentrations of metals. Not only are plants capable of adapting to
growth in media containing levels of metals that would be toxic to non-adapted
species, but these plants are able to assimilate the greater concentrations into
plant tissue. Dr . Ka'the Seidel and co-workers (20) at the Max Planck Institute
in Germany have shown that the metal absorption capacity of the bulrush,
Schoenoplectus lacustris, varies with the environment in which it is grown.
For example, in healthy lake water this plant absorbs 18 ppm (parts per million)
copper; whereas, in sewage adsorption is 50 ppm, an increase of 2.8 times.
For other metals, the increase is even greater—cobalt, 3 ppm in lake water as
opposed to 15 ppm in sewage, a fivefold increase; manganese, 260 to 2500, a
9.6-fold increase; chromium, 2.5 to 115.0, a 46-fold increase; nickel, 3.5 to 30.0,
an 8.6-fold increase; and vanadium, 6 to 115, a 19.2-fold increase.
As stated previously, information regarding the decomposition of hydro-
carbons in wetlands is limited. Valeila et al. (2) found circumstantial evidence
for the lack of movement of chlorinated hydrocarbons in their experimental studies
of salt marshes. While fiddler crabs exhibited harmful effects from exposure
to chlorinated pesticides present in applied sewage, the effect was absent two
meters downstream from the experimental site.
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Seidel's (20) experimental work with bulrushes proved that these plants
are capable of cleaving the aromatic ring of phenol and subsequently utilizing
the end products in their metabolism. Other hydrocarbons for which these inves-
tigators have obtained varying degrees of success utilizing treatment by marsh
plants include pentachlorophenol and cyanogen.
That seawater has a bactericidal effect on enteric bacteria has long been
established; however, no information was found in the literature regarding survival
of these organisms in artificial marine wetland situations. DeJong (12), in his
studies of experimental ditches planted in rushes and reeds, obtained highly
significant average reductions of 99.9% in the most probable number (MPN/ml)
of bacteria utilizing a 10-day detention time. Employing secondary activated
sludge effluent as a feed, Spangler (3) was able to obtain reductions of 90-99.7%
in coliform bacteria following only 5-hour detention periods in an experimental
pond populated with softstem bulrush (Scirpus validus) . Although reductions
in the numbers of potentially pathogenic microorganisms by passage through
wetlands is extremely good, and probably better than for either the trickling
filter or activated sludge treatment systems (12), nevertheless, there remains
the possibility of a disease outbreak from this source.
MACROPHYTES
Although a number of aquatic macrophytes, including alligator weed, duckweed,
and submersed vascular plants have been studied for the reclamation of wastewaters,
by far the greatest emphasis has been placed on the utilization of water hyacinths.
Water hyacinth, Eichhornia eras sip es (Marts.) Solms, is a native of South
America. Introduced into the United States in 1884, the species spread rapidly
and became established in waterways of several southern states. Due to rapid
growth, problems such as obstruction of water flow and water loss through transpi-
ration resulted. Weed control programs were initiated in 1899; early control
measures involved mechanical procedures later replaced by the use of herbicides.
Holm, Weldon, and Blackburn (21) estimated a loss of $43 million in the southeastern
United States during 1956 despite extensive control efforts.
Water hyacinths are widely distributed in the tropical and subtropical regions
of the world. Generally, the geographical area in which water hyacinths thrive
is bounded by 32 N and 32 S latitude. One of the fastest growing of aquatic
macrophytes, the number of water hyacinth plants doubles every 10 to 15 days
under favorable conditions. Penfound and Earle (22) have reported water hya-
cinth mats having densities of 125 to 184 tons per acre. Growth studies reported
by Wolverton and McDonald (23) indicate that one acre can produce 800 to 1,600
pounds of water hyacinth per day.
Waste water treatment systems, utilizing water hyacinths, have been proposed
for the removal or degradation of nutrients, organic materials, trace metals,
solids, and microorganisms. Robinson et al. (24) discuss design of systems
with respect to hyacinth growth rates and degrees of nutrient removal required.
For tertiary treatment they estimate that 31 to 156 acres would be required for
a throughput of 1 mgd at an annual production rate of 20 tons/acre. Participants
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of an EPCOT Technology meeting at Walt Disney World in Florida (25) concluded
that about 15 acres of water hyacinths could process 1 mgd of municipal wastewater.
A plan was developed to design a water hyacinth system for the tertiary treatment
of sewage coupled with the production of useful products from the biomass.
A variety of uses have been evaluated for harvested water hyacinths, including
animal feed, compost, fertilizer, paper products, conversion to methane, and
alcohol production. Based on a study to evaluate the economics and processing
of water hyacinth products for cattle feeding, paper-making, and compost, Bagnell
et al. (26) indicate that compost may be the best use, since this product had
the highest value with the lowest processing cost. In tests involving anaerobic
fermentation of water hyacinth, Wolverton, McDonald, and Gordon (27) found
that the biogas produced contained a high percentage of methane. At an incubation
temperature of 36 C, non-contaminated plants yielded 8.9 ml methane per gram
wet weight, while nickel-cadmium contaminated plants yielded 11.3 ml methane
per gram wet weight. Methane content of the total bio-gas produced was 69.2%
and 91.1%, respectively.
In the study of a drainage canal receiving municipal effluent from the Gregory,
Texas Wastewater Treatment Plant, Dinges (28) noted a mean reduction in BOD 5
of 35.4%. The canal surface area was 1.2 acres with a throughput of 140,000
gallons per day. Dinges (29) found that the mean BOD and COD decreased dramatic-
ally through a pilot system composed primarily of water hyacinth pond units
receiving stabilization pond effluent from the Williamson Creek Waste Water Treat-
ment Plant at Austin, Texas. The pilot system, occupying a surface area of
0.14 acres with a detention time of about 5 days, yielded mean reductions in
BOD 5 from 19 mg/1 to 3 . 5 mg/1, BOD 10 from 108 mg/1 to 20 mg/1, soluble BOD 5
from 8.1 mg/1 to 2.2 mg/1, COD from 82 mg/1 to 32 mg/1, soluble COD from 55
mg/1 to 30 mg/1 and TOC from 15.3 mg/1 to 9.8 mg/1.
In laboratory scale investigations Wolverton, Barlow, and McDonald (30)
found that the BOD 5 of raw sewage was reduced 97% utilizing water hyacinths
compared to 61% for the plant-free control and the BOD 5 of secondary effluent
was reduced 77% compared with 6% for the control following 7 days exposure.
An experimental hyacinth lagoon at Orange Grove, Mississippi, studied by Wolverton
and McDonald (31,32) for a period of one year, showed a reduction in BOD 5
for varied rates of flow. The hyacinth lagoon which received effluent from an
aerated primary and secondary lagoon series had a surface area of 0.28 hectares
and a volume of 6.8 million liters. During two months operation at a flow of
437,000 liters/day, a BOD 5 reduction of 75% and a TOC reduction of 31% was noted.
Operation for four months at 870,000 liters/day resulted in a 79% reduction of
BOD 5 and a 26% reduction of TOC . Four months at 1,059,000 liters/ day resulted
in a 66% reduction in BOD 5 and a 25% reduction in TOC. Reductions in BOD 5
of 60% and TOC of 34% were noted for two months of operation at a flow of 1,892,500
liters/day.
Wolverton and McDonald (31,33) evaluated a single cell sewage lagoon located
at Bay St. Louis, Mississippi, in terms of utilizing water hyacinth to upgrade
the effluent. The lagoon had a surface area of 17.5 hectares and a domestic waste-
water influent of about 3 .8 million liters/day. An enclosed area of 2. 5 hectares
around the point of discharge contained water hyacinth. Over a four-month period,
a 60% reduction in BOD 5 occurred from 39 mg/1 to 16 mg/1.
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Binges (28) found that total dissolved solids reduction was 59.3% for an expand-
ing water hyacinth population in a drainage canal at Gregory, Texas. The mean
total suspended solids for the pilot unit at the Williamson Creek Treatment Plant
(29) decreased from 46 mg/1 in the influent to 7.1 mg/1 in the effluent and mean
volatile suspended solids decreased from 40 mg/1 to 5.2 mg/1.
In laboratory scale tests utilizing water hyacinths at the National Space Tech-
nology Laboratories (NSTL), Wolverton, Barlow, and McDonald (30) found that
total suspended solids were reduced 75% compared to 15% for the plant-free control
following a 14-day exposure period. Wolverton and McDonald (31) found reduction
of 71% in total suspended solids at Orange Grove, Mississippi from a yearly average
influent level of 49 mg/1 to 14 mg/1. A reduction of 14% occurred in total dissolved
solids, the average influent level of 244 mg/1 being reduced to an average of
210 in the effluent. In the sewage lagoon at Bay St. Louis, Mississippi (32,33),
total suspended solids were reduced 88% from 125 mg/1 to 15 mg/1.
The water hyacinth population in a drainage canal receiving effluent from
the wastewater treatment plant at Gregory, Texas (28) , reduced nitrate from
7.24 mg/1 to 4. 06 mg/1 (43.9%) and phosphate from 16.4 mg/1 to 4.3 mg/1 (73.6%) .
The Williamson Creek pilot pond (29) also decreased nutrient concentrations:
mean level of ammonia was reduced from 2.1 mg/1 to 0.6 mg/1, total organic nitrogen
from 4.3 mg/1 to 1.2 mg/1, and phosphate from 15.4 mg/1 to 10.6 mg/1.
Reductions in nitrogen and phosphorus were noted in NSTL (30) laboratory
scale tests. In a 7-day exposure to raw sewage, the hyacinths removed 92%
of the total Kjeldahl nitrogen compared to 18% for the plant-free control and 60%
of the total phosphorus compared to 13% for the control. A water hyacinth-covered
lagoon at Orange Grove, Mississippi (31), reduced total Kjeldahl nitrogen by
47% and total phosphorus by 11%.
Ornes and Sutton (34) found that available phosphorus in static effluent
from an activated sludge treatment system was significantly reduced by water
hyacinths. After one week the available phosphorus decreased from 1.42 mg/1
to 0.97 mg/1 (32%); following two weeks exposure, the level was 0.41 mg/1 or
a 71% decrease from the initial concentration. In a related study (35) utilizing
duckweed, these investigators obtained over a 90% reduction in the phosphorus
content of sewage effluent after the first four weeks of an eight-week test period.
For the entire eight-week study period, phosphorus removal was 97%. McNabb
(36) , studying an aerobic pond populated principally by submersed flora (Potamogeton
foliosus, Elodea canadensis, and Ceratophyllum demersum), estimated that
with controlled harvesting, 20-25% of the total phosphorus input and 50-70% of
the total nitrogen input would be removed at a detention time of 28 days during
the growing season.
Several laboratory scale experiments utilizing water hyacinth have been
conducted involving the uptake of heavy metals from static water systems. Wolverton
and McDonald (37) found that up to 0.176 mg of lead and 0.150 mg of mercury
was removed per gram of dry plant material in a 24-hour period. Wolverton (38)
reported removal of up to 0. 67 mg of cadmium and 0. 50 mg of nickel per gram
of dry weight of water hyacinth for a 24-hour exposure period. Related removal
figures for alligator weeds were 0.101 mg of lead after 24 hours and 0.153 mg
of mercury after a 6-hour exposure period. Wolverton and McDonald (39) noted
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that 0.439 mg of silver, 0.568 mg of cobalt, and 0.544 mg of strontium was removed
from solution per gram of dry weight of water hyacinth for a 24-hour exposure
period. Comparable values for alligator weeds were silver, 0.439 gm; cobalt,
0.130; and strontium, 0.161 mg. Sutton and Blackburn (40) found that increasing
the concentration of copper sulfate pentahydrate (CSP) resulted in an almost
linear increase of the copper content of the roots of water hyacinths. At a concentra-
tion of 0.25 ppm of copper in the treatment solution, the copper content of the
plant roots was 41 ppm. With an increase in concentration of the treatment solution
to 16 ppm, the content of the roots increased to 14,801 ppm.
Based on laboratory experiments, Wolverton, Barlow, and McDonald (30)
estimated that water hyacinths had the potential to remove 0.61 kg of cadmium,
0.042 kg of lead, 0.036 kg of mercury, and 0.12 kg of nickel per acre per day
provided mature plants were harvested every 24 hours.
Wolverton and McKown (41), in static water studies, found that 36 mg of
phenol was removed in 72 hours per gram dry weight of water hyacinth. Estimates
were that water hyacinths had the potential for removing 160 kg of phenol/ hectare
in a 72-hour period.
In related studies, these investigators (32) noted that water hyacinths were
not effective in the removal of fecal coliform bacteria from sewage effluent. At
the Williamson Creek Pilot System, however, Binges (29) found that fecal coliform
concentrations were reduced from a mean of 2,536 per 100 ml in the influent
to a mean of 98 per 100 ml in the effluent.
INVERTEBRATES
A variety of animal organisms that feed directly on phytoplankton cultured
in ponds receiving municipal wastewaters has been studied in an effort to develop
a biological method for the clarification and purification of these waste effluents
while concurrently producing a byproduct of economic value. Organisms being
considered include Daphnia and related species (water fleas) , Artemia (brine
shrimp), and assorted bivalve mollusks (oysters, clams, and mussels).
In a series of studies conducted on an experimental Daphnia culture unit
receiving effluent from a waste stabilization pond, Dinges (28,42,43) found mean
BOD 5 reductions to be 69% and 79%, while COD values were reduced 67% and 55%.
Detention time for these studies was 11 days with a BOD 5 loading rate of 35 to
44 pounds/acre/day. Volatile suspended solids decreased 83-86% during the
experimental periods . At a Daphnia population density of 2,000 organisms
per liter, Frook (44) obtained an 80% reduction in suspended solids within 100
minutes.
Trieff, et al. (45), in a static laboratory study culturing the marine algae
Tetraselmis in wastewaters for use as a food source for brine shrimp, found
significant decreases following feeding in the overall values for BOD 5 and suspended
solids from 318 to 23 mg/1 (93.0%) and 120-20 mg/1 (83%) , respectively. An additional
algae stage was employed to further reduce these values.
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As regards the utilization of soluble nutrients in the Daphnia culture unit,
Dinges (43) makes the following comment: "Soluble nutrient minerals were not
removed in passage through the culture unit. Phosphate levels remained about
the same, and nitrates and organic-bound iron increased." Nutrient values
reported by Trieff (45) indicate that following the feeding of Tetraselmis algae
to Artemia, effluent levels for phosphate and nitrate were reduced from 20 to
10 mg/1 (50.0%) and from 30 to 7 mg/1 (77%) below the amounts originally measured
in the raw sewage culture medium.
While no reports were found on the effects of metals on Daphnia or brine
shrimp, mollusks are known to accumulate heavy metals present in the environment.
Clams and oysters, placed in creeks that drained plots fertilized with sewage
sludge, contained significantly higher concentrations of cadmium, but not lead
or zinc (2) . Hence, the investigators assumed that more cadmium than zinc
or lead was flushed from the fertilized marsh plots. No appreciable differences
in the amount of growth or percent survival of the oysters and clams was noted,
however.
Domestic wastewaters are known to contain elevated concentrations of metals
due to various treatment control procedures and additions from household products.
Kerfoot and Jacobs (46), culturing oysters on phytoplankton grown in a 1: 4
mixture of domestic effluent-filtered seawater, found that metal concentrations
of zinc, copper, cadmium, chromium, lead, and nickel declined in the cultured
oysters after the 45th day of a 102-day test. They attributed the lack of metal
accumulation to dilution of the effluent by seawater and the increased growth
of the oysters, with dilution effects being primarily responsible. It was concluded
that oysters may be propagated in a wastewater-seawater medium without raising
the danger of metal contamination.
In a related study employing the same effluent-seawater ratios containing
deliberately elevated concentrations of the previously mentioned metals, Kerfoot
and Redmann (47) observed that, in general, a concomitant rise in the content
of these metals in the oyster tissue also occurred. Of the six metals, lead showed
the more abrupt rise. From these studies the authors were able to formulate
a series of permissible levels for each metal in the following categories: algae,
shellfish, human acute, human chronic, and pollution alert. A final suggested
guideline of permissible levels was offered, encompassing all categories.
The retention and survival of pathogenic and potentially pathogenic bacteria
and viruses following passage through invertebrate waste treatment systems
have been studied. Dinges (42,43) reported reductions of 72.1% for total coli-
forms and 98.7% for fecal coliforms in the effluent from the Daphnia culture ponds.
In the saline effluent resulting from brine shrimp culture, Trieff (45) obtained
99.9% reductions for both coliforms and enterococci. No enterococci and an insignifi-
cant number of coliforms—3.7 per 100 Artemia organisms—were isolated from
tissue specimens, but were assumed to be associated with the algae present
in the gut of the brine shrimp.
In a comprehensive series of studies conducted at the Woods Hole Environmental
Research Laboratory, Metcalf (48) found that not only enteric viruses present
naturally in sewage, but also exogenously added viruses, including polio, were
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taken up and retained by both juvenile and adult oysters. Depuration efforts
were successful in most instances; however, on rare occasions virus was recovered
from shellfish tissue after 6 days. The author concluded that in its present state
of development, the production of shellfish for human consumption from domestic
waste effluents is not feasible from a public health standpoint.
FISH
Three approaches have been explored for the culture of fish utilizing municipal
sewage: 1) fish stocking directly into sewage lagoons; 2) addition of sewage
effluent to fish ponds; and 3) conversion of sewage into lower food chain organisms,
such as algae and microinvertebrates prior to discharging into fish ponds.
Tsai (49) provides an excellent review of these approaches as well as an assessment
of the merits of each.
The majority of experiments reported, involving the use of sewage for the
culture of fish, have been oriented toward evaluating the suitability of sewage
as a culture medium and establishing rates of fish production. Low levels of
dissolved oxygen, susceptibility to disease, water property changes, and presence
of toxic materials are among the technical problem areas that have been noted
for culture of fish utilizing sewage. There is little question, however, as to
the nutritional value of municipal sewage for the culture of fish (50) . In sewage
ponds owned by the Bavarian Power Company at Munich, Germany, 500 kilograms
of carp, Cyprinus carpio, was produced per hectare/year with a slow exchange
of water. In a rapidly flowing stream having a high sewage content in West
Java, carp confined to bamboo cages yielded 50 or more kilograms per square
meter of cage surface or 500 metric tons per hectare.
Tsai (49), in a discussion of the use of fish ponds for sewage purification,
indicates that the ponds have proved very satisfactory in many instances as an
advanced sewage treatment process. Kisskalt and Ilzhofer (51) found that effluents
from fish ponds had oxidizability values only slightly greater than those of natural
waters and that the disposal of such wastewaters presented no difficulties. Fathead
minnows were successfully cultured in a sewage stabilization system by Trimberger
(52) . The system consisted of five oxidation ponds operated in a series. Initially
stocked at one pound per acre, subsequent harvesting after six months yielded
378 pounds of minnows per acre. A decrease in turbidity was also noted for
the minnow-stocked ponds.
Several species of fish were stocked by Coleman et al. (53) in the last four
cells of a sewage oxidation pond system at the Quail Creek Plant located northwest
of Oklahoma City. The serially operated system received about 1 mgd of raw
domestic wastewater, and the average cell size was about 6. 5 acres . The first
two cells were aerated; the third and fourth cells were each stocked with 25,000
two- to four-inch channel catfish; and the fifth and sixth cells each received
750 adult golden shiner minnows. Five pounds of fathead minnows and 175 three-
inch Talapia nilotica were stocked in the third cell. Although not stocked, black
bullhead catfish, green sunfish, and mosquito fish were present in the system.
During a four month period of operation in the summer and early fall, BOD 5
decreased from 184 mg/1 in the raw sewage to 6 mg/1 in the effluent of the final
cell. Suspended solids were reduced from 197 mg/1 to 12 mg/1, and volatile
suspended solids from 131 mg/1 to 6 mg/1.
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Bozko et al. (54) found that secondary sewage effluent, subjected to further
treatment in ponds containing fish fry, showed a reduction of 20% for total nitrogen
and 40% for orthophosphate. Coleman et al. (53) found that total nitrogen decreased
from 18.94 mg/1 to 2.74 mg/1 for the Quail Creek lagoon system. Ammonia nitrogen
decreased from 12.67 mg/1 to 0.12 mg/1, and organic nitrogen from 6.10 mg/1
to 2.17 mg/1. Total phosphorus in the Quail Creek system decreased from 9.0
mg/1 in the raw sewage to 2.1 mg/1 in the effluent of the sixth pond.
In experiments to grow carp in domestic sewage effluent from the Rye Mead
sewage works near Hoddesdon, England, Noble (55) determined that accumulation
of mercury in the fish tissue was not a serious problem. Although the bottom
mud of the pond contained 1.0 ppm mercury on a dry weight basis, mercury
levels in the carp did not exceed 0.02 to 0.04 ppm.
Coleman et al. (53) found that fecal coliform decreased for the Quail Creek
system from 3.05 x 106 per 100 ml to 20 per 100 ml. Carpenter et al. (56) analyzed
179 fish and 77 water samples for enteric indicator bacteria and microbial pathogens
in the Quail Creek system. While essentially 99.9% of the indicator organisms—
total coliforms, fecal coliforms, and fecal strepococci—were removed following
passage through the second cell, there remained a low residual of organisms
that persisted in the effluent throughout treatment by the sixth and final cell.
Tests for the direct isolation of known pathogenic microorganisms revealed three
isolates—two enteric bacterial species, and one viral organism—none of which
were found in water samples collected past the second treatment cell. No pathogens
were found in the fish sampled.
INTEGRATED SYSTEMS
Experimental units that combine several types of organisms rather than focus-
ing on one or two types of organisms for treatment or utilization of municipal waste-
water are considered to be integrated systems. Some of these systems are examined
in their entirety while others are evaluated on the basis of individual organismal
components. Such systems are highly structured and often display complex food
chain interrelationships.
Aquatic plants or primary producers which utilize solar radiation to convert
nutrients and carbon dioxide to organic matter form the basic population component
for all integrated systems. It has been estimated that the maximum photosyn-
thetic production possible for freshwater and marine communities is around 200
metric tons fresh weight per hectare per year (57, 58) . Direct conversion of
all aquatic plants to animal tissue, assuming an efficiency of 15%, would result
in a crop of 30 metric tons per hectare per year of herbivores. Further conversion
to carnivores could result in a crop of 6 to 12 metric tons per hectare per year.
In practice, however, highly enriched culture systems are operated well below
their capacity due to the balance that must be achieved between producers and
consumers and the changes in rates of metabolic functions associated with major
environmental variables.
An excellent discussion is provided by Ryther et al. (58) concerning the
factors which influence the development of aquatic populations in highly enriched
environments. Relevant items discussed include the processes of population
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succession in natural environments as compared to those of highly enriched environ-
ments, the problems associated with uncontrolled enrichment of natural systems,
and the potential yield of well-managed eutrophic systems. In general, the authors
conclude that enriched systems are relatively unstable, failing to develop a fully
diversified community and that a high degree of control and management is required
to avoid inefficiencies and detrimental effects .
Dinges (28) determined the performance of a 5-step biological treatment
system designed to treat effluent from a sewage stabilization pond. The culture
unit, 280 feet long and 30 feet wide, was divided into four pond segments by
stacked rock barriers. The unit was two feet deep, with the exception of a 900
square foot area 8-foot in depth in the midsection of the second pond. The theoreti-
cal detention time for the system was 5.3 days. Water hyacinths, snails, duckweed,
scuds, and insects were present in the first pond. The second pond contained
zooplankton and duckweed. The third pond contained shrimp and aquatic plants,
while the final pond contained fish.
During a five-month period of operation, the integrated freshwater treat-
ment system functioned to achieve significant improvements in water quality.
The BOD 3 was reduced from 15 mg/1 in the influent to 3. 5 mg/1 in the effluent,
and BOD 20 from 90 mg/1 to 18 mg/1. The reduction in COD concentration was
43% from 70 mg/1 to 40 mg/1; suspended solids from 35 mg/1 to 7 mg/1 or by 75%.
Total organic nitrogen decreased from 4.8 mg/1 to 1.2 mg/1, and ammonia 95%
from 2.1 mg/1 to 0.1 mg/1. Fecal coliform and chlorophyll a were reduced by
92% and 99%, respectively.
Extensive research has been conducted at Woods Hole Oceanographic Institition
(59-66) directed towards the development of an integrated food chain system
for the treatment and/or utilization of secondary sewage effluent mixed with various
proportions of seawater. Several food chain combinations have been tested.
Among the organisms incorporated in the integrated systems are marine phytoplank-
ton, bivalve mollusks, fin fish, lobsters, polychaete worms, and seaweed.
Ryther (59) states, "The dual objectives of the system are to remove nutrients
from treated wastewater prior to its discharge to the environment (i.e. , a biological
tertiary sewage treatment process) and, at the same time grow commercially-
valuable crops of shellfish with secondary crops of lobster, flounder, and seaweeds.
Goldman et al. (65) evaluated a prototype process during eleven weeks of
summer operation. The system contained marine algae, oysters, and seaweed
in series. A mixture of 20% secondarily treated wastewater and 80% filtered seawater
was fed to the system. After a significant phytoplankton population developed
in the marine algae unit, one half of the pond volume was harvested each day.
The hydraulic residence periods for the oyster growth unit and the seaweed
growth unit was 1.62 and 0.23 hours, respectively. Efficiency of removal of
inorganic nitrogen in the system was 95%, with 45-60% removal for phosphorus.
The particulate carbon load was reduced from 4690 yg/min to 686 yg/min by
the oyster culture unit, resulting in a removal efficiency of 85.5%.
Ryther (63) developed and evaluated a pilot-plant scale integrated aqua-
culture system at the Environmental Systems Laboratory of the Woods Hole Oceano-
graphic Institution. The system was composed of continuous flow-through ponds
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for the culture of marine phytoplankton and raceways for the culture of shell-
fish and seaweeds. The American lobster and the winter flounder were stocked
in the shellfish raceways to feed on shellfish wastes and dense populations of
small invertebrates. Various concentrations of secondary sewage effluents combined
with seawater were fed to the system during the first year of operation. Maximum
phytoplankton production on an ash-free dry weight basis was 12 g/m2/day.
Mean phytoplankton production was 3 g/m2/day during the winter, 6 g/m2/day
during the spring and fall, and 9 g/m /day during the summer. Maximum seaweed
production on an ash-free dry weight basis was 16 g/m2/day. Mean seaweed
production was 3 g/m2/day during the winter, 5 g/m2/day during the spring
and fall, and 13 g/m2/day during the summer. During the first year of operation,
only limited success was obtained in the culture of shellfish due to poor growth
and high mortality.
The mass flow of inorganic nitrogen for the phytoplankton-oyster-seaweed
pilot plant system was determined for one month of operation. Total nitrogen
removal efficiency including the seawater input and output was 89.3%. When
nitrogen values for seawater input and output were subtracted, however, the
sewage effluent nitrogen removal efficiency was 93.6%. The maximum nitrogen
removal rate was 10.8 Ibs/acre/day for the phytoplankton growth unit and the
mean annual removal rate was 5.15 Ibs/acre/day. The maximum nitrogen removal
rate for the seaweed growth unit was 5.4 Ibs/acre/day with a mean annual re-
moval of 2.25Ibs/acre/day.
During the second year of operation of the pilot plant system, Ryther (59)
found that production and nitrogen removal capacities for the phytoplankton growth
unit were similar to those achieved during the first year of evaluation.
Culture experience with the American oyster (Crassostrea virginica) and
hard clams (Mercenaria mercenaria) indicated that these organisms have slow
growth rates and high mortality. Lack of success utilizing these shellfish species
was attributed to inferior and unsuitable food, since the phytoplankton cultures
were dominated by the marine algae, Phaeodactylum tricornutum, during most
of the year. Recent efforts have been directed toward selection of shellfish species
that can readily utilize the dominant phytoplankton species, since growth of
more desirable algal species as a food source for the forementioned mollusks
has not been achieved.
Two species of seaweed, Neoagardhiella baileyi and Gracilaria foliifera,
were evaluated during the second year of operation. Yields exceeded those of
earlier studies with a mean annual dry weight of 15 g/m2/day for N. baileyi
and 9 g/m2/day for G. foliifera. Results obtained from the operation of the seaweed
growth unit have been so favorable that experiments are being conducted on
seaweed as a one-step culture unit for nutrient removal.
Metcalf (48), in a two-year study of the integrated culture system at the
Environmental System Laboratory at Woods Hole Oceanographic Institution, evaluated
virus transmission through the aquaculture food chain. Based on results of
recovery tests utilizing virus concentration techniques, an average of 1 x 106
plaque forming units (PFU) of enteric viruses were calculated as the daily sewage
input into the system during the summer and fall months. The discharge waters
of the system were calculated to contain about 1 x 10** PFU of viruses each day
for a reduction in virus number of 99%.
20
-------
ECONOMIC EVALUATION
The major difficulty noted in economic analysis of aquacultural wastewater
treatment systems is the lack of verified data regarding design. In most cases
efficiency of treatment, production rates, and reliability of the systems being
evaluated are not well established. Although design data are based on available
published characteristics, estimates of water quality and rates of production
are often highly tentative and subject to a number of extrapolation assumptions.
More comprehensive and reliable economic evaluations, however, will not be
possible until design data are available for operation of aquacultural treatment
processes for a broad range of environmental variables, system sizes, and biomass
production rates.
Limited economic assessments have been performed for four types of muni-
cipal wastewater treatment processes utilizing aquacultural components (10,67-
69). Freshwater systems comprising fish, water hyacinths and wetlands, and
an integrated marine system composed of phytoplankton, oysters, seaweed, lobsters,
and sea worms have been evaluated. The basis for evaluation of the freshwater
systems was comparison of costs per unit volume of municipal wastewater to
achieve a specified level of treatment. The marine system was evaluated by a
comparison of production costs and revenues from sale of organisms with a fixed
treatment value assigned per unit volume of municipal wastewater.
Robinson et al. (24) evaluated the performance and costs of a water hyacinth
process as tertiary treatment (Table 1) for comparison with other tertiary systems
(Table 2) . The system design is based on hyacinth ponds which receive 1 mgd
of secondary effluent having the following characteristics: 30 mg/1 suspended
solids, 35.7 mg/1 BOD, 21 mg/1 nitrogen, and 11 mg/1 phosphorus. Treatment
costs for the water hyacinth process are based on the construction of a completely
new facility rather than the upgrading of existing lagoon facilities. In the cost
analysis, it is assumed that final disposition of the harvested water hyacinth
entails no costs and produces no revenue.
For purposes of comparing the hyacinth-based with other tertiary wastewater
treatment systems, a standard for tertiary effluent was selected having 5 mg/1
suspended solids, 5 mg/1 BOD, 3 mg/1 nitrogen, and 1 mg/1 phosphorus. It
was concluded that the hybrid design (water hyacinth/chemical system) had a
cost advantage in Southern Florida when comparisons were made of those sys-
tems that would meet the requirements of the tertiary effluent standards selected.
Also noted was the fact that overall cost for the hybrid design could be reduced
approximately 20%—to a cost of about 40$ per 1,000 gallons—by utilizing lagoons
already in existence.
Henderson and Wert (67) determined the cost-effectiveness of wastewater
aquaculture utilizing fish as an alternative to conventional wastewater systems.
The evaluation was oriented toward small municipalities in the Southwestern
region of the United States. Costs for 15 wastewater treatment strategies were
compared for treating 200,000 gal/day of municipal sewage for a twenty-year
period (Table 3) . Costs for conventional treatment were adjusted to values given
in the Environmental Protection Agency Complete Urban Sewer Cost Index for
Dallas, Texas.
21
-------
Production estimates for stocking several individual species and for poly-
culture indicated that polyculture provided the greatest fish output (Table 4) .
Species included were golden shiner, channel catfish, goldfish, bigmouth buffalo,
largemouth bass, and bluegill. Estimates of potential values from sale of fish
were based on recent published values and direct price quotes (Table 5) . Since
estimates of revenue for polyculture exceeded those for culturing individual
species, the cost effective analysis was based on polyculture for the eleven strategies
that contained aquaculture stages .
The efficiency of the 15 strategies, in terms of percentage reduction of pol-
lutants is given in Table 6. A raw sewage influent having 210 mg/1 BOD5, 230
mg/1 suspended solids, 11 mg/1 total phosphorus, 30 mg/1 TKN, and 30 mg/1
total nitrogen was assumed.
Based on cost and effectiveness, aquaculture stages in combination with
conventional stages appear to provide lower cost alternatives than conventional
wastewater treatment systems alone. Henderson and Wert (67) analyzed the
cost-effectiveness of the 15 strategies utilizing the multiple objective level approach.
The first objective level was compared in terms of BOD5 and suspended solids
(Table 7) while the second objective level was compared for nutrients (Table
8) . The authors (67) state, "In all cases when an aquaculture system is capable
of achieving a given BOD5 and SS objective, the aquaculture strategy is the most
cost-effective. Not only is the aquaculture the most cost-effective, but in every
case the cost differential between the aquaculture strategy and the conventional
strategy is substantial. The minimum savings associated with aquaculture are
found for objective C, where aquaculture cost are 62 per cent of conventional
costs, and the maximum cost saving is achieved for objectives A and B (28 per
cent of conventional costs) . Under the assumptions of this study there is no
aquaculture system that can achieve objective F. However, theoretically, aquaculture
systems should be able to reduce all plant nutrients and this limitation of aquaculture
probably reflects the methodology of this study plus the lack of knowledge with
respect to removal efficiency. Data is unavailable to substantiate this capability
of aquaculture. Only stage four ... of the conventional strategy 12 can reduce
BOD 5 and SS to such low levels, and then only at a staggering cost .... This,
of course, indicates that the potential savings from aquaculture might be massive
if future research shows that aquaculture can, in fact, reduce BOD and SS to
the levels defined in objective F.
"A similar cost-effective ranking of strategies is obtained when Phosphorus/TKN
objectives are employed. . . . Strategy 2, a Waste Stabilization Lagoon with
an Aquaculture Lagoon is the most cost-effective strategy for all objectives with
the exception of D. Again, data on water quality are insufficient to allow determination
of TKN values and, therefore, it is currently unknown, using the methodology
employed in this study, whether or not any of the alternative aquaculture systems-
will meet a TKN < 3. Strategy 2 will reduce P to 1.3 mg/1 and will thus meet
the requirements of objective D, but must be rejected as a result of the TKN unknown.
. . . The only strategy that meets those stringent levels of nutrient removal
is strategy 12 ....
"The cost saving associated with the use of aquaculture relative to convention-
al methods for nutrient reduction are even more significant than for BOD/suspended
22
-------
solids reduction. For objectives B & C, the cost of aquaculture represents only
6 percent of the cost of achieving that level of nutrient reduction using the most
cost-effective conventional system. This differential is striking and indicates
the potential of aquaculture for low cost nutrient reduction."
As a part of the Cypress Wetlands project at the University of Florida, rough
cost estimates were made for cypress dome wetland recycling of secondarily
treated wastewater (10) . Total treatment costs were determined for four rates
of sewage effluent input at three pipeline pumping distances. For a 50,000 gpd
rate of flow, the total system costs were 26.2, 52.0, and 84.4 cents per 1,000
gallons of sewage at distances of 1, 5, and 10 miles, respectively; for a 500,000
gpd rate of flow, system costs were 9.9, 16.1, and 23.7 cents per 1,000 gallons;
1 mgd rate of flow costs were 8.8, 13.0, and 18.3 cents, and 10 mgd costs were
7.0, 9.6, and 12.8 cents.
Smith and Huguenin (68) performed an economic evaluation of an integrated
marine aquaculture system based on the system developed at Woods Hole Ocean-
ographic Institution. Cost comparisons were made for regular heat and free
heat, nutrients from secondarily treated sewage effluent and a commercial fertilizer,
and several sizes of culture units. Tertiary wastewater treatment was assigned
a value of $.17/1,000 gallons. For the largest system, adequate for treating
the sewage of a city of about 100,000 people, an economic analysis indicated aquacul-
ture would be profitable if located in a warm climate or if free heat from a power
plant effluent could be obtained. Annualized operation costs were $8,841,150
with annual revenues of $12,578,900 for the system having no cost assigned for
heat. When a cost was assigned for heat in New England, operating costs of
the system became $40,073,230. Only about 5% of the total annual revenue,
or $595,000, was assigned as the actual cost for treatment of the wastes.
23
-------
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24
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TABLE 3. ESTIMATED COSTS OF TREATMENT BY STRATEGY AND STAGE*
Annual Costs $** 4/1,000 gal
Strategy 1. Waste Stabilization Lagoon
with Aquaculture Raceway
Stage I Waste Stabilization
Pond C =
O =
TI =
Stage II Aquaculture Raceway C =
O =
R =
TI =
17,433
8,500
25,933
9,660
5,877
-20,749
-5,212
35.5
-7.1
T2 28.4
Strategy 2. Waste Stabilization Lagoon
with Aquaculture Lagoon
Stage I Waste Stabilization
Stage II
*Adapted
** C =
O
R =
TI =
T2 =
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0 = 8,500
TI = 25,933
Aquaculture Lagoon C = 3 , 668
0 = 7,373
R - -20,749
TI = -9,708
35.5
-13.3
T2 22.2
from Henderson and Wert (67), pp. 45-9.
1976 Capital Costs amortized at 5 7/8% for 20 years
1976 Operating Costs
Revenues from Aquaculture Component
Total Cost of Stage (negative values indicate a revenue)
Total Cost of Strategy
(continued)
26
-------
TABLE 3 (continued)
Annual Costs
£71,000 gal
Strategy 3. Waste Stabilization Lagoon
with Fish
Stage I Waste Stabilization
Stage I
a
Strategy 4 .
Stage I
Stage II
Stage III
Pond
Culture of Fish
in Stage I
Trickling Filter with
Aquaculture Raceway
Primary Treatment
Trickling Filter and
Secondary Sedimentation
Aquaculture Raceway
C =
0 =
Ti =
C =
O =
R =
Ti =
C =
O =
Ti =
C =
O =
Tl -
C =
O =
R =
Ti =
17,433
8,500
25,933
None
7,373
-20,749
-13,376
25,355
9,567
34,922
34,367
12,831
47,198
9,660
5,877
-10,616
4,921
35.5
-18.3
T2 17.2
47.8
64.7
6.7
T2 Il972~
(continued)
27
-------
TABLE 3 (continued)
Annual Costs 471,000 gal
Strategy 5 .
Stage I
Stage II
Stage III
Strategy 6.
Stage I
Stage II
Stage III
Trickling Filter with
Aquaculture Lagoon
Primary Treatment
Trickling Filter and
Secondary Sedimentation
Aquaculture Lagoon
Activated Sludge with
Aquaculture Raceway
Primary Treatment
Activated Sludge
Aquaculture Raceway
C =
O =
Ti =
C =
O =
Ti =
C =
O =
R =
Ti =
C =
0 =
Tl =
C =
O =
Tl =
C =
O =
R =
Ti =
25,355
9,567
34,922
34,367
12,831
47,198
3,668
7,373
-10,150
891
23,698
9,359
33,057
49,087
16,142
65,229
9,660
5,877
-7,342
8,195
47.8
64.7
1.2
T2 113.7
45.3
89.4
11.2
T2 145.9
(continued)
28
-------
TABLE 3 (continued)
Strategy 7 .
Stage I
Stage II
Stage III
Strategy 8 .
Stage I
Stage II
Stage III
Activated Sludge with
Aquaculture Lagoon
Primary Treatment
Activated Sludge
Aquaculture Lagoon
Annual
C =
0 =
Ti =
C =
O =
Ti =
C =
0 =
R =
TI =
Costs t/1,000 gal
23,698
9,359
33,057 45.3
49,087
16,142
65,229 89.4
3,668
7,373
-7,151
3,890 5.3
T2 140.0
Activated Sludge-Chemical
Addition with Aquaculture
Raceway
Primary Treatment
Activated Sludge with
Chemical Addition
Aquaculture Raceway
C =
O =
Tl =
C =
0 =
Tl =
C =
O =
R =
Ti =
21,537
7,858
29,395 40.3
54,317
17,099
71,416 97.8
9,660
5,877
-3,185
12,352 16.9
T2 155.0
(continued)
29
-------
TABLE 3 (continued)
Strategy 9.
Stage I
Stage II
Stage III
Strategy 10
Stage I
Stage II
Stage III
Annual
Activated Sludge -Chemical
Addition with Aquaculture
Lagoon
Primary Treatment C =
0 =
Ti =
Activated Sludge with
Chemical Addition C =
O =
Ti =
Aquaculture Lagoon C =
O =
R =
Ti =
. Activated Sludge with
Denitrification System
Primary Treatment C =
O =
Ti =
Activated Sludge C =
O
Ti =
Nitrification and
Denitrification C =
O =
Ti -
Costs (f/1,000 gal
21,537
7,858
29,395 40.3
54,317
17,099
71,416 97.8
3,668
7,373
-3,004
8,037 11.0
T 2 149.1
24,250
9,020
33,270 45.6
40,647
14,460
55,107 75.5
44,445
18,996
63,441 86.9
T2 208.0
(continued)
30
-------
TABLE 3 (continued)
Strategy 11
Stage I
Stage II
Stage III
Strategy 12
. Activated Sludge with
Coagulation Filtration
Primary Treatment
Activated Sludge
Coagulation Filtration
. Activated Sludge with
Annual
System
C =
O =
TI -
C =
O =
Tl =
C =
O =
Tl =
Carbon
Costs
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TABLE 3 (continued)
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35
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TABLE 7. COST EFFECTIVE COMPARISON OF SYSTEMS TO ACHIEVE ALTERNATIVE
LEVELS OF BOD 5AND SUSPENDED SOLIDS*
Alternative Objectives
mg/1
Objective A
BOD 5 < 30, SS < 30
Objective B
BOD 5 < 25, SS < 26
Objective C
BOD5 <_ 20, SS < 22.5
Objective D
BOD5 < 15, SS < 19
Objective E
BOD5 < 10, SS < 15
Objective F
BOD 5 < 5, SS < 7
Aquaculture
-------
TABLE . 8 . COST EFFECTIVE COMPARISON OF SYSTEMS TO ACHIEVE
ALTERNATIVE OBJECTIVE LEVELS OF PHOSPHORUS AND TKN*
Alternative Objectives
mg/1
Objective A
P < 9, TKN <_ 13
Objective B
P <_ 7, TKN <_ 9
Objective C
P < 5, TKN < 5
Objective D
P < 3 , TKN <_ 3
Aquaculture Cost, Aquaculture
-------
SECTION 4
EVALUATION OF RESEARCH PROGRESS
Of the various parameters selected for evaluation, the majority of information
found has been in the areas of organics, solids, and nutrients with a lesser amount
of data in the area of biologicals. With few exceptions, the fate and effect of
heavy metals and residual hydrocarbons on aquaculture systems has not been
adequately investigated.
Of the data reported there is a wide variation with respect to type of system
and mode of operation. Table 9 presents selected data reported by various investi-
gators to illustrate this problem. No attempt is made here to analyze differences
in operation or other factors which would influence these results. The wide
variation in reported results is indicated, however, for the same general type
system. Also of significance to this study are the serious omissions in data and
the lack of consistency in report
A large portion of the research activity in aquaculture utilizing municipal
sewage has emphasized production of organisms rather than treatment of wastewater.
In experiments conducted in brackish water ponds fertilized with municipal
sewage near Humboldt Bay in Northern California, Allen (70,71) studied survival
rates, growth, smelting, and health of salmon. Although the fish culture ponds
were reported to have lower total coliform, fecal coliform, and fecal streptococcus
counts than an adjacent oxidation pond and creek, the monitoring of other water
quality parameters was related to the environmental tolerances of fish populations
rather than effectiveness of treatment.
At the New Alchemy East Farm on Cape Cod, Massachusetts, McLarney and
Sherman (72) tested environmental variables influencing the production of midge
larvae. During the first season of testing Chironomus tentans, culture ponds
were fertilized with horse manure; a standing crop of only 11 gm/m2 (98 Ibs/acre)
was attained. In subsequent tests following refinement of culture techniques,
ponds fertilized with Milorganite (a sewage sludge-based soil conditioner and
fertilizer) has a production rate of 259 gm/m2 per week (2310 Ibs/acre) based
on summer and fall observations. Although water quality parameters related
to treatment effectiveness were not monitored, production rates are extremely
high for herbivores. Assuming a year-round culture capability for midge larvae
at the high rate, the annual production would approximate 60 tons per acre.
Many of the experiments involving culture of organisms in municipal waste-
water have consisted of either small-scale laboratory experiments or descriptive
studies in large systems where only limited control was possible. The research
efforts that have been successful from the standpoint of culture capability and
38
-------
treatment efficiency appear to be those in which the experimental facilities were
designed to provide an acceptable environment for the culture organisms. In
those cases having inadequate cultural controls or insufficient knowledge of
the organisms' requirements, problems usually develop regarding the stability
of the process for treatment of municipal wastewater.
Minimal research efforts have been directed toward selective breeding of
aquatic organisms . Bardach (50) points out that while many species of terrestrial
animals have been subjected to selection with spectacular results, carp and several
species of trout are the only aquatic animals over which genetic control has been
exercised. Growth rate, fleshiness or muscling, resistance to disease and crowding,
and tolerance of temperature variation are among the genetic factors that have
been influenced by selective breeding of these aquatic animals.
Animal species for culture in municipal wastewater have been chosen with
a view for production of a valuable product as well as treatment of wastewater.
Limits in culture capability have contributed to the complexities of obtaining
both objectives. Establishing reliable culture techniques for integrated or food
chain treatment processes has been particularly difficult. Experiences with
the marine phytoplankton-oyster-seaweed process studied at Woods Hole Oceanogra-
phic Institution provide a good example of the culture problems encountered
in integrated systems designed to remove nitrogen from wastewater, while producing
oysters as a primary product and seaweed as a secondary product (59) . Although
the experimental facility was well designed and contained elaborate environmental
control mechanisms, it was not possible for the researchers to maintain a phyto-
plankton population suitable as a food source for the American oyster. If the
major research emphasis becomes production of shellfish, the approach required
will be to develop technology for control of the predominating phytoplankton
species or, through screening tests, to select a species of shellfish that can utilize
the marine phytoplankton occurring naturally. Should nitrogen removal receive
the major emphasis, it will involve developmental research for a monoculture
seaweed system.
Although a significant amount of information related to municipal wastewater
aquaculture is available, perusal of the existing data indicates that discrepancies
still exist in certain areas of concern.
39
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-------
13. Small, M. M. 1976. Marsh/Pond System. Data Rpt. Brookhaven Natnl. Lab. ,
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42
-------
27. Wolverton, B. C. etal. 1975. Bio-Conversion of Water Hyacinths into
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30. Wolverton, B. C. etal. 1976. Application of Vascular Aquatic Plants for
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Philadelphia, Pa., Univ. Pennsylvania, pp. 141-149.
31. Wolverton, B. C. and R. C. McDonald. 1976. Don't Waste Waterweeds. New
Scientist 67: 318-320.
32. Wolverton, B. C. andR. C. McDonald. 1976. Water Hyacinths for Upgrading
Sewage Lagoons to Meet Advanced Wastewater Treatment Standards: Part II.
NASA Tech. Memorandum X-72730, Natnl. Space Tech. Lab. , Bay St. Louis, Ms.
33. Wolverton, B.C. and R. C. McDonald. 1975. Water Hyacinths for Upgrading
Sewage Lagoons to Meet Advanced Wastewater Treatment Standards: Part I.
NASA Tech. Memorandum X-72729, Natnl. Space Tech. Lab. , Bay St. Louis, Ms.
34. Ornes, W. H. and D. L. Sutton. 1975. Removal of Phosphorus from Static
Sewage Effluent by Water Hyacinth. Hyacinth Control J . 13: 56-58 .
35. Sutton, D. L. andW. H. Ornes. 1975. Phosphorus Removal from Static
Sewage Effluent Using Duckweed. J. Environ. Qual. 4:367-370.
36. McNabb, C. D. 1976. The Potential of Submersed Vascular Plants for Recla-
mation of Wastewater in Temperate Zone Ponds. In. Biological Control of Water
Pollution. Philadelphia, Pa., Univ. Pennsylvania, pp. 123-132.
37. Wolverton, B.C. andR. C. McDonald. 1975. Water Hyacinths and Alligator
Weeds for Removal of Lead and Mercury from Polluted Waters. NASA Tech.
Memorandum X-72723, Natnl. Space Tech. Lab., Bay St. Louis, Ms.
38. Wolverton, B.C. 1975. Water Hyacinths for Removal of Cadmium and Nickel
from Polluted Waters. NASA Tech. Memorandum X-72721, Natnl. Space Tech.
Lab. , Bay St. Louis , Ms .
39. Wolverton, B.C. andR. C. McDonald. 1975. Water Hyacinths and Alligator
Weeds for Removal of Silver, Cobalt, and Strontium from Polluted Waters. NASA
Tech. Memorandum X-72727, Natnl. Space Tech. Lab., Bay St. Louis, Ms.
40. Sutton, D. L. and R. D. Blackburn. 1971. Uptake of Copper by Water Hyacinth.
Hyacinth Control J . 9:18-20.
43
-------
41. Wolverton, B. C. and M. M. McKown. 1976. Water Hyacinths for Removal
of Phenols from Polluted Waters . Aquatic Botany 2: 191-201.
42. Binges, R. 1973. Ecology of Daphnia in Stabilization Ponds. Texas State
Dept. of Health Resources, Austin, Tx., pp. 133-136.
43. Dinges.R. 1974. The Availability of Daphnia for Water Quality Improvement
and as Animal Food Source. Iri Wastewater Use in the Production of Food and
Fiber-Proc. EPA-600/2-74-041. U. S. Environmental Protection Agency.
pp. 142-161.
44. Frook, D. S. 1974. Clarification of Sewage Treatment Plant Effluent with
Daphnia pulex. Thesis, Univ. of Toledo.
45. Trieff, N. M. et al. 1976. Sewage Treatment by Controlled Eutrophication
Using Algae and Artemia. In_ Biological Control of Water Pollution, J. Tour-
bier and R. W. Pierson, Jr., eds. Philadelphia, Pa., Univ. Pennsylvania,
pp. 231-239.
46. Kerfoot, W. B. andS. A. Jacobs. 1974. Permissible Levels of Heavy Metals
in Secondary Effluent for Use in a Combined Sewage Treatment-Marine Aqua-
culture System I. Monitoring During Pilot Operation. Iri Wastewater Use in
the Production of Food and Fiber-Proc . EPA-600/2-74-041. U. S. Environ-
mental Protection Agency, pp. 65-78.
47. Kerfoot, W. B. and G. A. Redmann. 1974. Permissible Levels of Heavy
Metals in Secondary Effluent for Use in a Combined Sewage Treatment-Marine
Aquaculture System II. Development of Guidelines by Method of Additions.
In Wastewater Use in the Production of Food and Fiber-Proc. EPA-600/2-74-
041, U. S. Environmental Protection Agency, pp. 79-101.
48. Metcalf, T. G. 1975. Human Enteric Ciruses in a Waste-Recycling Aqua-
culture System. Final Report for NSF Grant G. I. 38976. 27p.
49. Tsai, Chu-Fa. 1975. Effects of Sewage Treatment Plant Effluents on Fish: A
Literature Review. Chesapeake Res . Consortium Pub. No. 36, Univ. Maryland,
pp. 220-229.
50. Bardach, J. E. 1968. Aquaculture. Sci. 161: 1098-1106.
51. Kisskalt, K. and H. Ilzhofer. 1937. Purification of Fish-Pond Water. Arch.
Hyg. Bakt. 118: 1-66.
52. Trimberger, J. 1972. Production of Fathead Minnows (Pimephales promelas)
in a Municipal Waste Water System . Michigan Dept. of Natural Resources,
Fisheries Div. , (Mimeographed Rpt.) 5 pp.
53. Coleman, M. S. et al. 1974. Aquaculture as a Means to Achieve Effluent
Standards . Iri Wastewater Use in the Production of Food and Fiber-Proc.
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44
-------
54. Bozko, L. et al. 1967. Biological Ponds as the Third Stage of Sewage
Treatment. Caz . Woda Sanit. 40:201-202.
55. Noble, R. 1975. Growing Fish in Sewage. New Scientist 67: 259-261.
56. Carpenter, R. L. et al. 1974. Evauation of Microbial Pathogens in Sewage
and Sewage Grown Fish. In_ Wastewater Use in the Production of Food and
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57. Ryther, J. H. 1959. Potential Productivity of the Sea. Sci. 130: 602-608.
58. Ryther, J. H. etal. 1972. Controlled Eutrophication-Increasing Food Pro-
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Recycled Wastes . Woods Hole Oceanographic Inst. Tech. Rpt. 76-92,
Woods Hole, Ma. (Unpublished Manuscript)
60. Ryther, J. H. 1973. The Use of Flowing Biological Systems in Aquaculture.
Sewage Treatment, Pollution Assay, and Food Chain Studies. Woods Hole
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Manuscript)
61. Huguenin, J. E. and J. H. Ryther. Experiences with a Marine Aquaculture
Tertiary Sewage Treatment Complex. In_ Wastewater Use in the Production of
Food and Fiber-Proc. EPA-660/2-74-041, pp. 377-386.
62. Ryther, J. H. Microbes as Food in Mariculture. Annu. Rev. Microbiol. 29:
429-443.
63. Ryther, J. H. 1976. Preliminary Results with a Pilot-Plant Waste Recycling-
Marine Aquaculture System. In_Proc. Int. Conf. on Renovation and Reuse of
Wastewater Through Aquatic and Terrestrial Systems. N. Y. , Marcel Dekker.
64. Ryther, J. H. et al. 1975. Physical Models of Integrated Waste Recycling-
Marine Polyculture Systems. Aquaculture 5: 163-177.
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R. W. Pierson, eds. Philadelphia, Pa., Univ. Pennsylvania, pp. 197-214.
67. Henderson, U. B. and F . S. Wert. 1976. Economic Assessment of Waste Water
Aquaculture Treatment Systems. EPA-600/2-76-293, U.S. Environmental Pro-
tection Agency, Ada, Ok. , 107 pp .
68. Smith, L. J. and J. E. Huguenin. 1975. The Economics of Wastewater Aqua-
culture Systems. I.E.E.E. Conf. Record of Engr. in the Ocean Environment.
Ocean '75-Sept. 22-24, San Diego, Ca., pp. 285-293.
45
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69. Allen, G. H. 1976. Rearing Pacific Salmon in Saltwater Ponds Fertilized
with Domestic Wastewater . Sept. 1974-Nov. 1975 Data Report HSU-SG-10,
Humboldt State Univ. , Arcata, Ca. , 92 pp.
70. Allen, G. H. 1976. Rearing Pacific Salmon in Saltwater Ponds Fertilized
with Domestic Wastewater . Oct. 1975-Aug. 1976 Data Report HSU-SG-11,
Humboldt State Univ. , Arcata, Ca ., 99 pp.
71. McLarney, W. and M. Sherman. 1974. Midge Culture at New Alchemy East.
Aquaculture and the Fish Farmer . 1: 10-13 .
46
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-110
3. RECIPIENT'S ACCESSI ON" NO.
4. TITLE AND SUBTITLE
Municipal Wastewater Aquaculture
5. REPORT DATE
June 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
William R. Duffer and James E. Moyer
8. PERFORMING ORGANIZATION REPORT NO
9 PERFORMING ORGANIZATION NAME AND ADDRESS
Robert S. Kerr Environmental Research Lab.
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
- Ada, OK
10. PROGRAM ELEMENT NO.
1BC611
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above.
13. TYPE OF REPORT AND PERIOD COVERED
In-House
14. SPONSORING AGENCY CODE
EPA/600/15
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The developmental status of the aquacultural alternative for treatment and
reuse of municipal wastewater is reviewed. Major emphasis is given to the
reduction or fate of pollutants in such areas as organics, solids, nutrients,
heavy metals, residual hydrocarbons, and potentially pathogenic organisms.
Economic assessments of treatment and production rates for organisms are
included for several types of aquacultural processes. Aquacultural systems
considered include natural wetlands, artificial wetlands, macrophytes,
invertebrates, fish, and integrated or food chain units. Areas having high
potential for further research and development are identified.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Fishes
Aquaculture
Wastewater treatment (municipal)
Water Pollution
Aquatic plants
Invertebrates
Fresh water
Solids
Water reuse
Wetlands
Mar ine
Microorganisms
Organics
Heavy metals
Nutrients
68D
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisRepbrti
UNCLASSIFIED
21. NO. OF PAGES
53
20 SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
47
•ft- US GOVERNMENT PRINTING OFFICE 1978-757-14O/1304
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