EPA-600/2-84-154
September 1984
TECHNOLOGY ASSESSMENT
OF
WETLANDS FOR MUNICIPAL WASTEWATER TREATMENT
by
Henry C. Hyde, P.E.
Roanne S. Ross, P.E.
WWI Consulting Engineers
Emeryville, California 94608
Francesca Demgen
Demgen Aquatic Biology
Vallejo, California 94590
EPA Contract No. 68-03-3016
Project Officer
Jon H. Bender
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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PB85-1Cy6896
EPA-600/2-84-154
September 1984
TECHNOLOGY ASSESSMENT
OP
WETLANDS FOR MUNICIPAL WASTEWATER TREATMENT
by
Henry C. Hyde, P.E.
Roanne S. Roes, P.E.
WWI Consulting Engineers
Emeryvillef California 94608
Francesca Demgen
Demgen Aquatic Biology
Vallejo, California 94590
EPA Contract No. 68-03-3016
Project Officer
Jon H. Bender
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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TECHNICALREPORTOATA
Pfcaw read !nstr,,cnu,,g efl the ,r erie be lore ccrn l ,letlnrl
3.
2.
RECIP.EjvTS ACCESS’ N NO
?B3 1d6896
5 R 5PO T OATS
of Wetlands for Municipal • PERPORMING ORGANIZATION CODE
REPORT NO
Ross, and Francesca Demgen
S. PERPORMING ORGANIZATION
NAME AND ADDRESS
International
10. PROGRAM ELEMENT NO.
CAZB1B
11.C NTAACT
68—03—3016
AND ADDRESS
Research Laboratory - Cm., OH
Development -
Protection Agency
IS. TYPE OP REPORT AND PERIOD COVERED
Final Reoort
14. SPONSOR ING
EPA/ 600/14
H. Bender (513) 684-7620
and alternative technology provisions of the Clean
1977 (PL 95-217) provide financial Incentives to conrunitles
treatment alternatives to reduce costs or energy
conventional systems.. Some of these technologies have
developed and are not In widespread tise in the United
effort to increase awareness of the potential benefits of
and to encourage their implenientalonwhere applicable,
Environmental Research Laboratory has initiated this series
Technology Assessment reports. This document discusses the
and technical and economic feasibilty of using natural and
wetland systems for municipal wastewater treatment facilities.
EY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS b.I OENTIPIERS/OPEN_ENDED TERMS
a COSATI
15. SECURITY CLASS lTflui(.DoPfi —
Unclassified
to Public - 20. SECURITY CLASS (TIILI pge,
Unclassified
1 PdO.O rAGES
111
PRICE
EP a F.,,. Z 2O-I 573
1
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DISCLAIMER
The information in this document has been funded wholly or in
part by the United States Environmental Protection Agency under
Contract No. 68—03—3016 to Waste & Water International. It has
been subject to the Agency’s peer and administrative review,
and it has been approved for publication as an EPA document.
Mention of trade names or commercial products does not consti-
tute endorsement or recommendation for use.
11
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FOREWORD
The U.S. Environmental Protection Agency was created
because of increasing public and government concern about the
dangers of pollution to the health and welfare of the American
people. Noxious air, foul water, and spoiled land are tragic
testimonies to the deterioration of our natual environment.
The complexity of that environment and the interplay of its
components require a concentrated and integrated attack on the
problem.
Research and development are the necessary first steps in
problem solution, and involve defining the problem, measuring
its impact, and searching for solutions. The Municipal
Environmental Research Laboratory develops new and improved
technology and systems to prevent, treat, and manage wastewater
and solid and hazardous waste pollutant discharges from
municipal and community sources, to preserve and treat public
drinking water supplies, and to minimize the adverse economic,
social, health, and aesthetic effects of pollution. This pub-
lication is one of the products of that research and is a most
vital communication link between the researcher and the user
community.
The innovative and alternative technology provisions of
the Clean Water Act of 1977 (PL 95—217) provide financial
incentives to communities that use wastewater treatment
alternatives to reduce costs or energy consumption over
conventional systems. Some of these technologies have been
only recently developed and are not in widespread use in the
United States. In an effort to increase awareness of the
potential benefits of such alternatives and to encourage their
implementation where applicable, the Municipal Environmental
Re.search Laboratory has initiated this series of Emerging
Technol9gy Assessment reports. This document discusses the
applicability and technical and economic feasibilty of using
natural and artificial wetland systems for municipal wastewater
treatment facilities.
Francis T. Mayo
Director
Municipal Environmental Research
Laboratory
111
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ABS TRACT
Wetland is a general term which applies to different
aquatic habitat types. wetlands may be defined as an area
covered periodically or permanently with water of varying
depths and which supports hydrophilic vegetation. Wetlands may
be fresh or saline, and some are associated with larger bodies
of water.
There are various types of natural and artificial wetlands
being used for wastewater treatment: marshes, shallow ponds,
bogs, cypress domes, cypress stands, and swamps. All of the
wetland systems reviewed for this assessment were either fresh
or brackish, and treated domestic wastewater to various
degrees. A wastewater wetland may also provide the secondary
benefits- of wildlife habitat, and recreational and educational
opportunities.
The research completed on wastewater wetland systems is
extensive. Results of bench and pilot scale projects have
produced a number of full-scale systems. These full—scale
systems include artificial and natural marshes, peatlands,
swamps, marsh/pond/meadows and bogs.
Wastewater treatment in a wetland system is accomplished
through biological, physical and chemical reactions. Although
the processes involved are fairly well understood, there are
still questions as to the roles that individual reactions play
in the treatment process. To further complicate any attempt, at
modeling the treatment process, it is probable that the
proportion of significance assigned to each treatment reaction
varies with specific project conditions. The major components
of the wetland system which perform the wastewater treatment
are: algae, macrophytes (larger, rooted plants), bacteria,
zooplankton, and the substrate (bottom soils). I
A wastewater wetland system can provide primary,
secondary, or advanced treatment. The need for open land or
existing wetland areas makes this techn logy compatible with
areas outside of urban centers. Capital costs, operational
costs, and energy requirements are significantly less than
conventional treatment alternatives. Land acquisition and
proximity to the wastewater source are the major variables
• affecting cost.
iv
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CONTENTS
Disclaimer.
Foreword.
Abstract.
Figures
Tables. .
Acknowl edg ient
. . . . .
• . . . .
• . . . .
• S S • S
. . . . S
• . . . .
S
S
.3
.3
.6
.7
.
. . 38
. . 38
• . 38
. . 38
. . 38
. . 39
. . 39
. • 39
. S S S • S S • S S S S
. . . S • . . . . S S S S •
I S S • S • 5 S S • •
. . S S S S S S S
. S • S S • S • S S
S S S S S • S
ii
iii
iv
Vi 1
viii
ix
1
1
Section 1.
Section 2.
Section 3.
Section 4.
Technology Description. . . . . . . .
Introduction. . . . . . . . . . . . .
Process Flow Paths in Natural and
Artificial Wetlands. . . . . . . . .
Natural Wetlands . . . . . . . .
Artificial wetlands. . . . . . .
Common System Components and Modifications.
Recommendations . . . . . . . . . . .
Developmental Status of Wetland Systems
Introduction. . • . . . . . . . . . .
Summary of Research Findings. . . . .
Lab/Bench Scale Research Projects.
Pilot/Demonstration Scale Research
Projects. . . . . . . . . • . .
Full Scale Natural Wetlands Treatment
Projects. . . . . . . . . . . .
Full Scale Artifical Wetlands Projects
Design Data from Full Scale Wetlands
Fac 1ities . . . . . . . . . . . . .
Available Equipment and Hardware. . .
Technology Evaluation . . . . . . .
Process Theory. . . . . . .. . . . .
Introduction . . . . . . . . .
Wetlands Components. . . . . .
Plants. . . . . . . . . .
Soils . . . . . . . . . .
Bacteria. . . . . . . . .
Animals . . . . . . . . .
9
11
• 11
11
11
• 11
17
• 23
• 26
• 34
V
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Removal Mechanisms . . , . . . . .
BOD and Suspended Solids. .
- Bacteria and Virus. . . . . . .
Phosphorus. . . . . . . . .
Nitrogen. . . . . . . . . .
Heavy Metals. . . . . . . .
Refractory Organics . . . . . .
Constituent Removal Efficiencies.
Process Capabilities and Limitations.
Full Scale Design Considerations. . .
Introduction . . . . . . . . . . . .
Wetlands Treatment System Design
Specific Wetland Types . . . . .
Artificial Marsh. . . . . . . .
Marsh/Pond. ‘-. . . . . . . . . .
Lined/Vegetated Trenches. . . . o
Seepage Wetlands. . . . . . . .
Natural Marshes . . . . . . . .
Artificial Wetlands . . . . . .
Cypress Domes, Strands or Swamps.
Bogs and Peatlands. . . . . . .
Energy Analysis . . . . . . . . . . . .
Operation and Maintenance Requirements of
Wetland Treatment Systems. . . . . . .
Costs . . . S S S S S S •
Construction Cost. . . . . . . .
OperaUon and Maintenance Costs.
Section 5.
Comparison with Equivalent Conventional
Technology . . . . . . . . . . .
Introduction. . . . . . . . . . .
Cost Analysis . . . . . . . . . .
Cost Comparison. . . . . . . .
Energy Analysis . . . . . . . . .
. . . 65
. . . 65
. . . 67
. . . 75
. . .. 80
Section 6.
Section 7.
National’ Impact Assessment.
Potential Market. . .
Cost and Energy Impact.
Cost . . . . . S
Energy . . . . . .
Perspective . . . . . .
Cost . . S • S •
Energy . . . . . .
Marketability/Risk. . .
References and Contacts
• . . . . . • . . 86
• • . . . . • . . 86
. . • . • . . . . 86
. . . . . . . . . 86
. • . . . . . . . 87
. . . . . . . • . 88
• . . . . . . . . 88
. . . . . . . . . 90
. . . . . . . . . 90
. . S • S
. . 92
• 40
. 40
. 40
. 40
. 41
. 41
.4-2
• 42
• ‘45.
. 46
. 46
• 47
. 49
. 49
• 49
. 50
. 50
. 50
. 51
. 51
• 52
. 53
. 57
. 60
. 60
. 62
vi
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FIGURES
Number
1 Process Flow Diagrams — Natural and Arti-
ficial Wetlands . . . . . . . . . . . . . . . . 4
2 Arcata Experimental Marsh Cells—Flow Diagram. . 14
3 Vermontville Michigan Seepage Wetland Process
Flow Diagram. . . . . . . . . . . . . . . . . . 33
4 Mt. View Sanitary District Wetland Process
Flow Diagram.. . . . . . . . . . . . . . . . . 33
5 Power Required to Overcome Friction Loss, for
Various Flow Rates. . . . . . . . . . . . . . . 54
6 Static Lift—Power Requirements. . . . . . . . . 56
7 Cost of Earthwork for Small Projects. . . . . . 61
8 Cost of Earthwork for Large Projects. . . . . . 61
9 Estimated Construction Cost of Pump Station. • 62
10 Average Annual Cost Comparison Secondary
Treatment . . . • • • • . . . . . . . • . . . • 77
11 Average Annual Cost Comparison — Advanced
System.. . . . • . . . • . . . . • . • . . . . 78
12 Capital Costs Comparison — Secondary System . . 79
13 Capital Costs Comparison — Advanced System.. . 81
14 Annual O&M Costs Comparison — Secondary Treat—
in ent. . . • . . . • • . . . . . . • . • . . . • 82
15 Annual O&M Costs Comparison - Advanced Treat-
ment. • • • . . • . . . . . • . . • . . . . . . 83
16 Comparison of Energy Demands. . . . • • . . . . 85
v i ,
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TABLES
Number
1 Wetlands Types. . . . . . . . . . . . . . . . . 2
2 Distinguishing Characteristics of Various
Natural Wetlands Types.. . . . . . . . . . . . 5
3 Examples of Wetlands Vegetation . . . . . . . . 6
4 Summary of Removal Efficiencies from Pilot
Scale Wetlands Projects .. . . . . . . . . . . 13
5 Design Parameters for Arcata ,Experimental
Marsh Cells .. . . . . . .. . . . . . . . . . . 15
6 Unweighted Rank Order of Five Effluent Perfor-
mance Parameters. . . . . . . . . . . . . . . . 15
7 Water Quality Data, Weekly Mean Values for the
Experimental Marshes, City of Arcata,
California.. . . . . . . . . . . . . . . . . . 16
8 Mean Values from Long—Term Studiesat Brillion
Marsh . . . . . . . . . . . . . . . . . . . . . 18
9 Water Quality Data from Cypress Strands in
Wiláwood, Florida. . . . . . . . . . . . . . . 19
10 Average Annual Removal Efficiencies for Great
Meadows Wetland, Massachusfttts. . . . . . . . . 20
11 Three Year Summar P of Nutrient Removal from
Bellaire Wetlands . . . . . . . . .. . . . . . 20
12 Macronutrient Content of Glyceria Grandis
Biomass Above Ground, Cootes Paradise Marsh,
Canada. . . . . . . . . . . . . . . . . . . . . 21
13 Uptake of Metals by Plants, Cootes Paradise
Marsh, Canada . . . . . . . . . . . . . . . . . 21
14 Cypress Dome Water Quality. . . . . . . . . . . 22
viii
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15 Water Quality in seepage Wetland , Vermont—
yule, Michigan................ 24
16 Mt. View Sanitary District Wetland Water
Quality Data, 1975—1967. . . . . . . . . . . . 25
17 Neshaininy Falls Operational Results, Water
Quality . . . . . . . . . . . . . . . . . . . . 25
18 Neshaininy Falls Removal Rates .. . . . . . . . 26
19 Summary of Nutrient Removal Data from Full
Scale Wetlands. . . . . . . . . . . . . . . . . 27
20 Full Scale Wetland Systems in the United
States. . . . . . . . . . . . . . . . . . . . . 28
21 Design Data for Ful-1—Scale Facilities —
Natural Wetlands. . . . . . . . . . . . . . . . 29
22 List of Full—Scale Projects in the Design
Phase . . . . . . . . . . . . . . . . . . . . . 35
23 Wastewater Wetlands Equipment Suppliers . . . . 37
24 Dominant WetlandPlants . . . . . . . . . . . . 39
25 Contaminant Removal Mechanisms in Aquatic
Systems Employing Plants and Animals. . . . . . 43
26 Reported Ranges of Removal Efficiency for
Wastewater Constituents in Wastewater in
Natural and Artificial Wetlands . . . . . . . . 45
27 Wetlands Design Methodology . . . . . . . . . . 47
28 Unified Soil Classes with Hydraulic Conduc—
t ivity. . . . . . . . . . . . . . . . . . . . . 51
29 Preliminary Design Parameters for Planning
Artificial Wetlands Wastewater Treatment
Systems . . . . . . . . . . . . . . . . . . . . 52,
30 .Labor for Maintenance of Wetlands Treatment
Systems . . . . . . . . . . . . . . . . . . . . 58
31 Summary of Typical Maintenance Tasks. . . . . . 58
32 Cost of Artificial Membrane Liners. . . . . . . 63
ix
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33 Surface Area Required for Marsh Wetland
System. • . . . . • • . • . . . . . . . . . . . 67
34 Cost Estimate of Earthwork for Marsh Wetland
Systems • • • • • • • • • • 69
35 Cost of Land Acquisition for Marsh Wetland
Systems . . . . . . . . . . . . . . . . . . . . 69
36 Total Capital Cost for an Artificial Marsh Wet-
land System . . . . . . • , , • • . • • • • • 70
37 Annual Labor Requirements for Operation and
Maintenance of an Artifica]. Marsh Wetland
System. . . . . . . . . . . . . . . . . . . . . 71
38 Annual O&M Costs of wetlands Utility Vehicle.. 71
39 Annual O&M Costs for a Marsh Wetland System . 72
40 Estimated Costs for a Marsh Wetland System . . 73
41 Estimated Costs for a Marsh Wetland System . . 74
42 Estimated Costs for a Marsh Wetland System . . 75
43 Comparison Between Wetland and Conventional
System Annual Average Costs . . . . . . . . . . 76
44 Annual Energy Required by Marsh Wetland
System. . . . . . . . . . . . . . . . . . . . . 80
45 Comparison Between Wetland Systems and
Conventional Systems Annual Energy Require—
ments ., . . . . . . . . . . . . . . . . . . . . 84
46 Estimated Treatment Plants to be Constructed
Between 1978 and 2000 . . . . . . . . . . . . 87
47 Estimated Annual Average Cost of the
Anticipated Treatment Plants, 1978—2000 . . . . 88
48 Estimated Annual Energy Demands for the
Anticipated Treatment Plants. . . . . . . . . . 89
x
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ACKNOWLEDGMENTS
The following members of WWI Consulting Engineers staff,
US Environmental Protection Agency staff, and subcontractors
have participated in the preparation of this report.
WWI Consulting Engineers
Mr. Henry C. Hyde, P.E.* : Project Manager
Ms. Roarine Ross, P.E. : Project Engineer
Demgen Aquatic Biology
Ms. Francesca Demgen : Aquatic Biologist
US Environmental Protection Agency
Mr. John M. Smith, P.E.* : Chief: Urban Systems
Management Section,
Wastewater Research
Division
Mr. Robert- P.G. Bowker, P.E.* : Project Officer,
Wastewater Research
Division
* Current Affiliation:
Henry C. Hyde Henry Hyde & Associates
Star Box 605
Sausalito, CA 94965
John M. Smith J.M. Smith & Associates
Robert P.G. Bowker 7373 Beechmont Avenue
Cincinnati, OH 45230
xi
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SECTION 1
TECHNOLOGY DESCRI PT ION
INTRODU ION
The utilization of wetland for wastewater treatment has as
its base its historical/ecological function. Riverine wetlands
often occur where a stream enters a river, lake or bay. Here
the velocity of the tributary’s water drops and the silt
carried by the stream is deposited in the marsh, swamp or
peatland. Vegetation develops in this fertile, shallow area
and acts as a filters for water entering the marsh and larger
bodies of water. The wetland is a sink for nutrients and
organic debris during most of the year. The streams contin-
ually supply the wetland with nutrients, creating a highly
productive system. The system then can support a wide variety
of wildlife. Wetlands serve as important rearing grounds for
animals and fishes which live above the marshes in the streams
and below the marsh in the rivers, lakes and bays. The marshes
of this country’s great rivers have been employing this living
filter mechanism to treat domestic wastes for many years with
little recognition of their contribution towards meeting the
goals of the Federal Water Pollution Control Act Amendments of
1972 (PL 92—500) and the Clean Water Act of 1977 (PL 95—217).
The recent interest in the ability of wetlands to treat waste—
water is fostered by economic concerns and the acknowledgement
that wastewater may be viewed as a resource.
Wetland is a general term which applies to a number of
different aquatic habitat types. A wetland may be defined as
an area covered periodically or permanently with water of
varying depths and which supports hydrophilic vegetation. Wet-
lands may be fresh or saline, and some are associated with
larger bodies of water. Table 1 deScribes various types of
natural and artificial wetlands. Wetlands are similar to aqua—
culture systems; however, a distinction can be made. -
AquacUlture is the production of aquatic organisms,, both
flora and fauna, under controlled conditions, primarily for the
generation of food, fiber, and fertilizer. There is a separate
technology assessment as a part of this series which covers the
subject of aquaculture systems used for wastewater treatment.
1
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There are a number of types of natural and artificial
wetlands being used for wastewater treatment: marshes, shallow
ponds, bogs cypress domes, cypress stands, and swamps. All of
the wetland systems reviewed for this assessment were either
fresh or brackish, and treated domestic wastewater to various
degrees. A wastewater wetland may also provide the secondary
benefits of wildlife habitat, recreational and educational
opportunities, stream flow augmentation, and harvestable plant
byproducts.
Table 1. WETLAND TYPES (Reference 31)
Classification
Type
Description
-
Wetland located adjacent to
Riverine
rivers or streams; for
example, marshes, shallow
ponds, or wet meadows.
Wetland adjacent to or near
Laucustrine
lakes; for example, marshes,
-
shallow ponds, or wet meadows.
Natural
Pa lüstrine
Wetland isolated from open
bodies of water; for example,
bogs and cypress domes.
Tidal
Wetland areas subject to tidal.
action with various flooding
regimes. -
.
Marshes
Shallow depths with emergent
plants such as cattails and
bulrushes covering nearly the
entire surface. Basin may be
sealed or unsealed.
Artificial
Ponds
‘
Somewhat deeper than marshes
with an open water surface.
May contain submerged plants
and plants on the banks.
Marsh/Pond
A combination of the two
components above.
Trench
Narrow ditches, lined or
unlined, planted with
vegetation, usually bulrushes.
2
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The primary components of a wetland treatment system are
influent wastewater and a shallow, mostly vegetated basin with
or without a point source discharge. The submerged and emer-
gent plants, their associated microorganisms, and the wetland
soils are responsible for the majority of the treatment
effected by the wetland. Wastewater wetland systems can pro-
vide primary, secondary, or advanced treatment. The need for
open land or existing wetland areas makes this technology
compatible with areas outside urban centers. Capital costs,
operation costs, and energy requirements are low compared with
conventional treatment alternatives. Land acquisition and
proximity to the wastewater source are the major variables
affecting cost.
PROCESS FLOW PATHS IN NATURAL AND ARTIFICIAL WETLANDS
A wetland environment can be used to accomplish a variety
of levels of treatment a-nd the desired level of treatment of
the influent will affect the flow path. Comminuted, aerated,
raw sewage can be treated through a multi—cellular artificial
system. The water progresses through a series of plots until
the desired quality is reached. Primary or secondary effluent
could also serve as wetland influent. Process flow diagrams
for natural and artificial wetlands are shown in Figure 1.
Natura]. etlpnds
Natural marshes, bogs, cypress domes, and strands are all
in use as wa&tewater treatment systems. Table 2 describes
distinguishing characteristics of each wetland type. Very few
physical modifications are necessary to adapt a natural wet-
lands for treatment. Inlet structures are required except
when the wastewater has been discharged to a tributary upstream
of the wetland. Stand pipes, overflow weirs and discharge
pipes have been used to introduce the wastewater to the wet-
lands in a single location. It may be necessary to have
smaller multiple inlets to avoid erosion and provide even
distribution of the water over the entire surface of the wet-
land. In such cases, multiple—gated, aluminum irrigation pipe
has been successfully used. Depending on the configuration
of the wetland’s perimeter, a barrier levee may be necessary to
contain the wastewater. Any levees which become part of the
system should be constructed so that they can support a mainte-
nance vehicle. This allows access for maintenance of the
wetland and the levee itself. If the wetland lies in a deep
natural depression such as a bog, or it is contiguous with a
larger body of water, a barrier levee may not be required.
A natural wetland is normally an expansive area. Although
there are no physical barriers subdividing the wetland, often
3
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Evapotranspi ration
Influent — Effluent
+ +
Percolation
Possible Influents Wetland Vegetation Types Effluent Disposal
1. Aerated Raw sewage 1. Subnergents 1. Non—point discharge
2 Primary Effluent 2. flnergents 2. Percolation
3. Secondary Effluent 3. Floating 3. Point discharge
4. Threato ytes
A. bira]. j tIm
Evapotranspi ration Evapotranspi ration
Influent fluent
Percolation
Possible irifluents Wetland Vegetaton Types Effluent Variations
1. Aerated raw 1. Suth ergents - 1. Point discharge
sewage 2. Eknergents 2. Non—point
2. Primary Effluent 3. Floating discharge
3. Secondary Effluent 4. Threato ytes 3. Percolation -
Flc ,, Pattern Variations
1. &naller multiple cells.
2. Cells subdivided by internal levees.
3. Islands to direct fl rj
B. Artifi 1al 1F vk
Figure 1. Process flow diagra.s - natural arx1 artificial wetlarxk.
4 -
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Table 2. DISTI GUISHfl CBAR r 1STICs (P VARI(IJS 2URAL WE’flIA
Type
Vegetation
Thysical tharacteristica
Marshes
Cattails, bu]rushes,
duckweed. Suthiergents
and bank plants vary
with the locality,
1.5 m. deep. Vegeta-
tion often interspersed
with anall areas of o n
water.
Bog/
S agnum ness, leather-
Very few open water
Peatland
leaf, . sedges, willows,
I nse, thick, low vege-
tation.
areas. Often located in
a deep depression. May
be isolated from other
bodies of water.
Cypress Dane
Cypress trees, duckweed. Usually 0.4 — 10 ha. in
‘size. Shape — irregular
circles. No regular dis-
charge — occasional over—
fi ow.
Cypress
Trees: Cypress, willow,
Strand: Linear, flow-
strand/swamp
ash, others. Also marshy
areas, wet meadows,
shallow channels.
through systan. 3 amp:
Dense vegetation, van—
able shapes, depth less
•
thanl.5m.
it is composed of various habitat types. For example, a marsh
might have areas of open water among the emergents, or a peat—
land may have areas of water tolerant trees and shrubs in
addition to the sphagnum, leather leaf, sedges, etc. The
wetland may have established channels or the water may sheet
flow over the entire surface. The wetland often merges with a
broad open body of water, such as a river orlake. Peatlands,
isolated bogs, and cypress domes are an exception to this
process. They frequently have no surface discharge; instead,
all water loss is by percolation, evaporation, and/or
transpiration.-
A natural wetland usually has a diversity of plant species
indigenous to its location; Table 2 lists some common vege-
tation types. The plants are a component of the physical
process involved in wastewater treatment due to their direc—
tional effect on the flow of wastewater through the wetlands.
They also serve as a surface for colonization by bacteria,
algae and microorganisms which act upon the wastewater and
react with the vegetation. The four categories of plants which
5
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will influence the flow path of water are floating plants,
subrnergents, emergents, and phraetophytes (plants rooted on the
banks but growing out over the water). Table 3 gives examples
of each of these types of wetland plants. The type and density
of plants also influences the rate of evapotranspiration, hence
the total water volume.
Table 3. EXAMPLES OF WETLAND VEGETATION
Vegetation Type
Common Name
Latin Name
Floating
Duckweed
Waterlily
Lemna app.
Nymphaea app. -
Submergents
Pond Weed
Water Weed
Potamogeton app.
Elodea app
Emergents
Cattail
Buiruahes
Typha spp.
Scirpus app.
Phreatophytes
Smartweed
Fat Hen
Polygonum spp.
Atriplex spp.
The soils are an important process component. The
biological and chemical composition of the soil matrix deter-
mines the reactions possible for removal of pollutants. The
particle size and soil type also determine the percolation
capacity of the wetland.
Ar tificip1 etlan&
The physical processes of an artificial wetland are more
easily managed than in a natural wetlands. This ability to
manipulate the flow path allows more, efficient use of space.
Often natural wetlands used for wastewater treatment are very
large. The ability to control the flow and vegetation in an
artificial wetland allows treatment to occur in a smaller area.
An artificial wetland is usually composed of multiple
plots. Each unit normally has one inlet and discharge
structure. Additional structures are helpful to allow flow
path modifications for maintenance, dryingcycles, or treatment
variations. The flow within each plot can be directed by
islands, vegetation, internal baffles or levees, and
occasionally by mechanical devices. The number of wetland
units comprising the treatment system depends on the topography
6
-------
of the site, influent water quality and desired effluent
quality.
There are two types of artificial wetlands in use:
discharge and seepage. The former has one or more defined
discharge points. Seepage wetlands have no final discharge
point; instead the water percolates into the soils, evaporates
or transpires into the atmosphere.
The previous discussion on Natural Wetlands concerning
vegetation and soils also applies to artificial wetlands. When
an artificial wetland is created, some vegetation will need to
be planted. Cattails and various species of bulrushes and
reeds grow, nationwide; root stock for some species may be
transplanted to the new area. Seeds and root stock are also
available commercially. Levees and banks may be seeded with a
grass mixture. Native plants will then colonize the wetland
area and establish good cover and erosion protection. Har-
vesting has, generally been found not to be necessary. The
potential of harvesting wetland biomass for use in energy
production is being investigated. A high density of plants is
usually considered desirable. Dredging the substrate may be-
come necessary in the long term, perhaps every 15 to 20 years.
Routine harvesting, however, has not been necessary.
COMMON SYSTEM COMPONENTS AND MODIFICATIONS
Inlet structures of the following types can be found in
use: stand pipes, weirs, gate valves, and long aluminum
irrigation pipes with multiple flap gates. The first three
types have been used in artificial wetlands and cypress domes
while the last type has been used in natural wetlands including
cypress strands, bogs, and peatlands. Effluent discharge
structures can be weirs, gate valves, or flap gates.
The substrate (the wetland soils) is an important process
component. In some cases, the substrate may be porous and
therefore, reduce or eliminate point discharge from the
system. In other cases the substrate may be sealed and may
consist of native or imported clays, or an artificial sealer
such as a plastic liner. Plastic liners are sometimes used in
artificial trench systems.
Artificial substrates can be used to enhance or replace
vegetation in artificial wetlands. They are colonized by
aquatic invertebrates, bacteria, and periphytic algae, thereby
enhancing the food chain. These organisms are the same as
thosá found on the submerged portions of plant stems. There-
fore, when artificial substrates are used in open water area!,
they provide some of the functions of emergent vegetation.
7
-------
wind driven circulators or electric aeration devices can
be used to influence the flow path and enhance circulation or
aeration.
8
-------
SECTION 2
RECOMI4ENDAT IONS
The use and reliabi-lity of wetland as wastewater treat-
ment systems should increase as additional successful
experience is gained in the future. Based on this assessment,
the following recommendations are made regarding the imple-
mentation of wetland wastewater treatment technology:
o Construction and Design of Artificial Wetland
sins . Various methods of basin construction should
be studied to determine the most cost—effective
method. The design of the basin should be optimized
to minimize energy requirements and to facilitate
minimum operation and maintenance of the basins.
o Engineering Design Criteria . Research projects
should be developed to test design criteria (i.e.,
surface and-organic loadings) for both artificial and
natural wetlands. This information is necessary for
design of the different wetland types in various
geographical locations (warm and cold climates).
o Impacts on Natural Wetlands . There is much contro-
versy regarding the impact of introducing wastewater
to a natural wetland. Research should be directed at
determining what and how significant the impacts are.
o Labor Requirements . Available information regarding
O&M labor requirements is limited. Operating
facilities should document actual labor requireme.nts
to enable other agencies to accurately estimate labor
demands and operational procedures. -
o Removal Efficiencies . As shown in Table 26, there ‘is
limited data on the removal efficiencies for
artificial wetlands. Presently there is very limited
published data on the removal efficiency of the
following parameters for artifical wetlands: total
• solids, -dissolved solids, suspended solids, TOC., COD,
nitrogen, heavy metals, coliforms, and pathogens.
For natural wetlands, there is also very limited
published data on the removal efficiency of the
9
-------
following parameters: refractory organics, pathogens
and coliforms.
o Costs . Accurate documentation of the—construction
and O&M costs should be maintained by operating
facilities. This information would be helpful for
future Cost estimates. Existing documentation of
cost is poor. -
o Information Transfer . Publication of successful
project information in widely read professional
publications is needed to inform wastewater agencies
of wetland wastewater treatment opportunities.
Guidance documents published by EPA for distribution
by state and regional regulatory and funding agencies
to wastewater management agencies would be useful in
promoting the use of wetland treatment technology.
Currently, many state and regional agencies are not
well informed regarding the benefits of wetland
treatment technology.
10
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SECTION 3
DEVELOPMENTAL STATUS OF WETLAND SYSTEMS
INTRODUCTION
The purpose of this section is to give a broad overview of
the wetlands treatment research data currently available. Data
from one bench scale project, seven pilot/demonstration scale
projects and fifteen full—scale projects were utilized in this
effort. Many volumes of available data have been condensed
into this summary to provide an accurate picture of wetland
system performance.
The pilot scale projects described are artificial wetlands.
A brief description of each project and a summary of removal
- efficiencies for key water quality parameters are given. More
emphasis is placed on full—scale projects due to their size and
operational status. Design criteria and performance data are
included for the full scale facilities.
SUMMARY OF RESEARCH FINDINGS
Lab/Bench Scale Research Projec.f.
Lakshman (Reference 21) created an artificial, bench—scale
marsh using plants containing bulrush and cattail to treat raw
municipal sewage. Initial concentrations of total phosphorus
(TP) and total Kjeldahl nitrogen (TKN) were 3.9 — 29 mg/I.
and 10.3 — 44.0 mg/I. respectively. Up to 90 percent removal
was achieved in less than 20 days. Lakshman reports that
vegetated tanks had continuous removal ability whereas gravel
filled tanks reached a saturation level for nutrient removal.
Pi1ot/Demonstrati n. Scale Research Proj ect
Small (References 25 and 26) and Woodwell (Reference 38)
et. al. tested the ability of two artificial systems:
marsh/pond and meadow/marsh/pond over a five-year period. The
application rates varied from 420 — 855 cu in/ha—day of comini—
fluted, aerated raw sewage. Typha and Leinna (cattail and duck—
weed) were the major vegetation types. Total suspended solids,
total coliform and turbidity were high in the effluent. These
are, however, normal by—products of a wetland ecosystem. The
high iron and manganese levels reflected elevated levels in the
11
-------
drinking water supply. The remaining parameters were equiva-
lent to the •quality achieved by conventional secondary
systems. Table 4 contains a summary of removal rates from the
pilot scale wetlands projects.
Cederquist and Roche (Reference 4) conducted a three—year
study of treatment and reuse in a pilot project adjacent to the
Suisun Marsh in Cordelia, California. An approximately 5 ha
site was divided, into four shallow ponds and two marshes which
received secondary effluent at an average flow rate of 950
cu rn/day. Application rates to the ponds were 1.38 Cu rn/ha/mo
(two ponds) and 2.76 cu rn/ha/mo (two ponds). Table. 4 Contains -
a summary of removal efficiencies.
Nute (Reference 23) describes a pilot study of a 74 -sq in
surface area pond with artificial substrates in place of vege-
tation in Martinez, California. The pond discharges to a
subsurface irrigation system for the growth of redwood trees.
The pond receives 13.6 cu rn/day of secondary effluent; one—
tl ” 1 ird is utilized by the irrigation system and two—thirds is
discharged. Creation of wildlife habitat, and improvement of
water quality are the goal of the system. Table 4 contains a
summary of removal rates.
Spangler, Sloey and Fetter (Reference 27) in Wisconsin
studied water quality, improvements by plants in four settings:
greenhouse, experimental basins, pilot plant and natural marsh.
The natural marsh will be discussed in the review of full—scale
facilities section. In the greenhouse study, three species of
bulrush and iris received 21 liters of primary effluent on a
five—day batch basis. Removal rates are given in Table 4.
Softstem bulrush ( Scirpus validus ) was chosen for test pur-
poses in the experirnental basin because of the good removal
rates in the greenhouse studies. These basins were lined with
PVC plastic and the vegetation was planted in gravel. Experi-
ments with both primary and secondary effluent were performed
using an application rate of 1.9 liters/minute to give a
retention time of five hours for the secondary effluent and
ten days for the primary effluent. Table 4 lists removal rates
achieved. A study was also conducted using softstem bulrush in
a “pilot plant” trench, with approximately 112 sq in of surface
area. A ten—day retention time was used. The results for tests
on both primary and secondary effluent are listed in Table 4.
De Jong (Reference 9) studied artificial marshes for the
treatment of sewage from campgrounds in the Netherlands. These
studies are prerequisite to larger municipal wetlands treat-
ment systems. Table 4 shows the reduction in BOD, COD, total
phosphorus and total Kjeldahl nitrogen achieved by the bulrush
and reed marshes.
12
-------
TABLE 4. SUMMARY OF REMOVAL EFFICIENCIES FROrI PILOT SCALE WETLAND
PROJECTS, IN PERCENT
a) Suspended Solids
b) Sunniier
c) Winter
d) Kjeldahl Nitrogen
I—
(A)
Authors
S
Influent Type
.
Wetland Type
Wetland
Area
BOD 5
COD
Total
P
SSa
Nitrate
& Nitrite
Ammonia
Small &
WQodwell
Aerated
Raw Sewage
Meadow/marsh/pond
Marsh/pond
2475 m 2
4700 m 2
92
89
90
88
78
71
89
88
73
53
86
58
Cederquist
& Roche
Secondary
Effluent
Marsh
5 ha
--
--
75
8O-.S
Incr_WC
incr. -s
20-W
Nute
Secondary
Effluent
Pond with artifi-
cial substrates
75 m 2
60
--
25
79
46
22
DeJong
Raw sewage
Marsh
1 ha
96
93
80
85 d
Spangler
Primary
Effluent
Primary
Effluent
Greenlouse
Trehches
Experimental .
basins, trenches
7200 cm 2
9 m 2
98
87
86
75
82
25
--
82
--
——
--
-—
Sloey
lined & vegetated
Fetter
Secondary
Effluent
S
87
24
17
69
--
--
Primary
Effluent
Secondary
Effluent
Pilot Plant
Trenches,
lined and
vegetated
57 m 2
77
38
71
44
37
64
24
77
——
--
--
--
-------
Two additional pilot/demonstration projects will be
mentioned; both are currently in operation and data are being
collected. Both projects will supply needed information in
defining the treatment capabilities and design Criteria for
artificial wetlands.
Wile (Reference 36) describes research being conducted in
two towns in Ontario, Canada. At Listowel there are two a ti—
ficial marshes receiving raw aerated sewage and an additional
two are planned which will receive lagoon effluent. The flow
rates to these four artificial marshes will vary between 10—43
cu m/ day. There is also a marsh/pond/marsh system operating
ir series which will receive lagoon effluent, loaded at rates
between 50 — 200 Cu rn/day. The town of Bradford’s sewage
treatment plant is located adjacent to a natural cattail marsh,
approximately 1400 sq m in area. The background levels of
nutrients will be documented for two years prior to the
addition of partially treated wastewater. -
The City of Arcata, California is conducting a pilot
project to: 1) evaluate the feasibility of using secondary
wastewater to enhance the productivity of a freshwater marsh;
and 2) test the effectiveness of marshes to reliably treat
stabilization pond effluent to tertiary standards (Reference 19
and personal communication with Gearheart). Twelve 0.004 ha
experimental marshes are being operated with variable flow
rates, detention times and vegetation. Figure 2 shows the
design scheme of the twelve plots and Table 5 the design para-
meters. Current studies are... scheduled to be completed in July
1982. Data gathered for the first six—month period are tabu—
lated in Table 6 and 7 (Reference 13).
FIGURE 2. Arcata experimental marsh cells — flow diagram (Reference 13).
14
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Table 5. DESIGN PARAMETERS FOR ARCATA EXPERIMENTAL MARSH
CELLS (Reference 19)
Cell Detention Inf].uent Vegetation
Number Time flow rate Percent coverage
(Hours) (liters/mm) Emergents Floating Submergents
1 56 61 70 15 25
2 28 61 65 15 15
3 56 61 50 80 ‘ ——
4 28 ‘ 61 55 100 10
5 112 30 85 20 5
6 56 30 90 15 5
7 112 30 65 100 20
8 56 30 30 100 5
9 224 15 75 55 20
10 112 15 70 40 25
11 224 15 65 100 15
12 112 15 65 100 10
Table 6. UNWEIGHTED RANK ORDER OF FIVE EFFLUENT PERFORMANCE
PARAMETERS - LOWEST RANKING REPRESENTED HIGHEST
PERFORMANCE, ARCATA (Reference 13)
Marsh Cell Number
Parameter 1 2 3 4 5 6 7 8 9 10 1112
BOD 8 31011 7 2 912 4 1 6 5
I’ FR 8 .6 11 12 7 5 10 9 4 1 2 3
NH3 1011 8 912 6 5 7 3 4 2 1
Total Coliform 8 9 12 10 5 3 7 11 4 2 6 1
Fecal Coliform 9 5 12 10 11 4 8 7 2 3 6 1
TOTAL - 43345351422039-4619 11 26 11
15
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TABLE 7. Wathr Quality Data, Weekly Mean Values for the Experimental Marshes,
City of Arcata, California (Reference 13)
Non-Filterable
COD Residues Ammonia
mg/i removal mg/i removal mg/i removal
July 29, 1980 throuqh October 16, 1981
21.0
75 11.5
73 8.9
60 13.5
51 13.8
85 7.0
84 5.9
52 12.7
58 12.3
87 8.2
84 4.2
74 6.8
81 4.6
BOO
Marsh
Cell No.
mg/i removal
Nitrate
mg/i removal
Turbidity
NTIJ
INFLLJENT
27.0
82.5
26.0
1
6.9
75
59.5
28
6.5
2
9.2
65
59.7
28
6.9
3
11.6
57
63.2
23
10.2
4
14.7
45
70.4
14
12.6
5
6.7
75
54.6
34
3.7
6
6.1
77
54.6
34
4.1
7
10.4
61
65.9
20
12.4
8
12.0
55
65.2
21
10.9
‘-
°
9
10
5.5
3.6
79
86
59.9
53.1
27
36
3.2
4.0
11
4.9
81
60.7
26
6.7
12
6.9
74
56.2
32
4.8
October
1980
through
January
1981
INFLUENT
23.9
31.7
26.6
1.02
22.2
1
13.0
46
9.5
70
22.7
14.6
0.71
30
13.3
2
8.2
66
6.5
79
23.1
13.0
0.99
3
11.0
3
14.0
41
8.5
73
22.0
15.0
0.73
28
15.3
4
14.7
38
10.9
66
22.4
15.7
0.68
33
15.6
5
12.2
49
5.3
83
23.3
13.5
0.71
30
‘
13.0
6
7.9
57
5.0
84
20.6
22.5
0.74
27
10.8
7
13.3
44
10.9
65
20.4
23.3
0.79
23
15.2
8
15.4
36
10.5
66
20.8
21.8
0.77
25
13.7
.
9
8.5
69
5.5
83
18.4
30.8
1.21
-19
9.0
10
7.8
67
5.4
83
•
18.5
30.4
1.34
—31
7.6
11
12.0
50
8.2
74
17.4
34.5
0.80
22
7.9
12
10.1
58
7.9
75
16.5
37.9
1:25
—23
8.5
-------
predominant emergents are cattail and bulrush; predominant
floating vegetation are water starwort ( Callitriche palustris )
and duckweed, and the predominant submerged vegetation is
pondweed ( Potamogeton foliasus) .
Two general trends on the effects of vegetation for
improving water quality have been identified: 1) emergents and
submergents have a greater positive effect than floating vege—
station; 2) a band of vegetation covering the complete width of
the cell has a greater positive effect than sporadic patches
covering the same amount of area. The data generated from this
project will provide information to help in sizing wetlands for
specific levels of treatment and to define the role vegetation
plays in the treatment process.
Full Scale Natural Wetland. Treatment Projects
Spangler (Reference 27) et. al. studied Brillion Marsh
which receives approximately 757 Cu m/day (0.2 mgd) from the
City of Brillion, Wisconsin sewage treatment plant, as well as
natural tributaries. ll parameters studied, except total
solids and dissolved solids, were reduced by the marsh. Of all
the parameters, BOD and coliform levels achieved the greatest
reductions. Table 8 contains results from a one—year study.
Station I is in a creek, tributary to the marsh, above the
sewage effluent discharge. Station II is below the discharge
and prior to the marsh. Station III is within Brillion Marsh.
Other studies were also done on vegetation nutrient levels and
harvesting effects.
Kadlec (Reference 16) describes his studies of the Houghton
Lake Pe tland Marsh (Michigan) which has received 3790 to 7570
Cu m/day (1—2 uigd) of secondary effluent for five consecutive
summers. Data concerning standard water quality parameters,
nutrients, heavy metals, biomass, pathogens, soils, vegetation
nutrient levels, algae, vertebrate and invertebrate fauna have
been collected and analyzed in volumes of reports. All nitro-
gen and phosphorous were removed within a two—hectare area.
Total alkalinity, PH, and hardness decreased rapidly from the
influent point. Chlorides pass through the wetland with little
change, while the chemical oxygen demand increased. Lead,
copper, nickel and boron levels were below the limits of de-
tection. No soil erosion or plant mortality occurrred. Sus-
pended solids deposited close to the discharge.
Boyt (Reference 2) et. al. studied a mixed hardwood swamp
and cattail/duckweed marsh in Wildwood, Florida, which has
received 946 cu rn/day (0.25 mgd) of poor quality, secondary ef-
fluent for twenty years. Analyses have been done for water
quality, sediment nutrient levels, biomass, tree growth and
bacteria. Nitrogen, phosphorous and dissolved oxygen levels
17
-------
Table 8. MEAN VALUESa F 1 LaZ- 1 M S’1UDI T BRfl 1 LIC P RSH
(Reference 27)
Pri itary Creek
Effluent
fran
Marsh
S
Re&cticzi
Station 1 Station II
above waste- bela,i waste-
Par ter water distharge water disctharge
-‘
BOD 5 6 27
5
81.5
31 106
60
43.4
Orthophospate 1.3 3.1
2.9
6.4
Total Thos orous 1.3 3.4
3.0
13.4
Conductivity (umho) 1540 1065
983
7.7
Turbidity (J’lU) 26 20
11.3
43.5
‘
Nitrate 1.8 1.2
0.6
51.3
Coliform
(log col 100 ml ) 4.76 5.54’
4.68
86.2
pH 7.9 7.8
7.4
—
Total. Solids 955 707
767
—8.5
suspended Solids 154 127
90
29.1
Dissolved Solids 801 580
677
—16.7
aAll values are mg/i unless otherwise indi ted in parentheses.
can be seen in Table 9. Fecal coliform and streptococci levels
declined rapidly within the swamp. The sediments did not show
a build-up of nutrients. Tree growth was more rapid in the
experimental swamp with wastewater nutrients present than in
the swamp area without wastewater.
the discharge of 379
to a 10 ha (25 acre)
in May 1979. Research
quality, vegetation,
Kappel (Reference 17), reports on
cu rn/day 0.1 mgd)of secondary effluent
bog in Drumniond, Wisconsin, which began
encompasses four major areas: water
small animals, water and nutrient budgets.
18
-------
Table 9. WATER QUALITY DATA F M CYPRPSS S ND fl WU 1 mJCC ),
(Reference 2)
Nutrient
Strand
Influent
3.7 Ian in
fran Inlet
Levels of
Dissolved Oxygen
Total Phos *iorus
6.4 mg/i
0.12 mg/i
Control
2.4 zng/l
Total Nitrogen
15.3 mg/i
1.61 mg/i
st
2.8 mg/i
Data from standard chemical and nutrient analyses
Summarized through August 1979 show no changes in water quality
in the bog’s discharge. Nutrient levels in the vegetation thus
far are within normal levels for non—wastewater bog plants.
The animals to date have not been affected.
The Delaware River estuary system receives large loads of
industrial and domestic wastewater. Whigham and Simpson (Ref-
erence 35) studied a portion of this vast system. The 500 ha
(1240 acre) Hamilton freshwater tidal marsh receives 26,495
cu rn/day (7 mgd) of secondary effluent from the Hamiltion
Township, New Jersey wastewater treatmer t facility. Vege-
tation, soil, algae, and water quality have been studied.
Vascular plant productivity is high, ranging from 150—2000 g/sq
rn/year. Peak algal biomass is less than that for vascular
plants and tidal inudflats. Water quality varies with the tide
and the season. The authors conclude that the vegetated high
marsh acts as a nutrient sink during summer months, and the
pond—like area performs a similar function in the winter.
Yonika (Reference 39) describes the effects of a 2,390
cu rn/day (0.61 mgd) discharge of secondary effluent by the Town
of Concord, Massachusetts to the 19 ha (48 acre) Great Meadows
National Wildlife Refuge. The wetland is composed of various
vegetation types and water depths. Removal efficiencies have
been calculated during various seasons and vegetation types.
Average values are listed in Table 10.
Th. e Village of Bellaire, Michigan, discharges approximately
1.lx10 Cu in (30 xng) of secondary effluent to a 15 ha (36 acre)
wetland from approximately May to November each year. Kadlec
and Tilton (Reference 15) have published three data reports
containing water chemistry and water budget data. Nutrients
are of prime concern because the marsh discharges to a
recreational lake. Table 11 contains a three—year summary of
total dissolved phosphorus and dissolved nitrogen data.
19
-------
Table 10. AVERAGE ANNUAL
MEADOWS WETLAND,
Table 11.
REMOVAL EFFICIENCES FOR GREAT
MASSACHUSETTS (Reference 39)
ThREE lEAP. SUMMARY OF NL7 IENT REMOVAL PROM BELLAIRE WE’ILANDS,
MIOIIGAN (Reference 15)
Th$-. 1 fli sn1 v i Phnsrthôru
Dissolved Nitrogen
1976
3.80
0.58
85
75
75
66.9
1977
4.95
0.46
9].
80
92
134.8
1978
10.84
0.61
94
80
85
118.7
(a) Mass average concentrations are weighted ty the actual amount of
water entering or leaving the wetland.
(b) Concentration reductions are based on mass average concentrations.
Cc) Gross r novals are based on total inputs and outputs.
(d) Net removals are based on inputs and outputs less background
value for the wetland.
Mudroch and Capobianco (Reference 22) describe studies done
on Cootes Paradise’s feeder streams and marshes. Poor quality
treated wastewater of an unstated volume from the town of
Dundas, Canada, enters the marsh. The 520 ha (1300 acres)
wetland has received this dischatge since 1919. Nutrients,
productivity and heavy metals in vegetation and sediments were
studied. Tables 12 and 13 report metal and nutrient levels in
selected plants. Sediments show increased levels in lead,
Criteria
Percent Reduction
Ammonia Nitrogen
58%
Nitrate Nitrogen
20%
Nitrite Nitrogen
No
reduction
Total Kjeldahl Nitrogen
35%
Total Phosphorus
47%
Ortho Phosphorus
Biochemical Oxygen Demand
49%
67%
(a)
(a)
(b)
Cc)
(d)
Influent
Effluent
Conc.
Gross
Net
Wastewater
Year
Mass Avg.
mg/i
Mass Avg.
mg/i
Reduction
%
Removed
%
Removed
%
Added
1000 Cu
m
1976
2.40
0.09
96
91
94
66.9
1977
3.48
0.11
97
88
92
134.8
1Q7R
2.45
0.16
94
12
77
118.7
20
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Table 12. - MA U1 IENT CZ3N’1 NT OF CLYCERIA ( AM)IS BIOMASS ABCWE J!1),
QXY] S PARADISE MARSH, CA1 (Reference 22)
p N
Mg
% gin? gi n? gin? %
g/n? % g/n?
Locality Apil
West Pond 0.51 3.1 1.80 10.8 3.2 19.2 0.57
Long Valley 0.40 2.0 2.20 11.0 2.20 11.0 a.32
Desj ardines
canal 0.34 1.7 2.30 11.5 2.00 10.0 0.70
3.4 0.22 1.3
1.6 0.16 0.8
3.5 0.24 1.2
.iune
West Pond 0.13 6.2 1.40 67.2 1.50 72.0 0.50
Long Valley 0.21 6.8 1.80 48.6 1.70 45.9 0.40
Desj ardines
c aria1 0.13 5.2 1.20 48.0 1.50 60.0 0.70
24.0 0.18 8.6
10.8 0.24 6.4
28.0 0.20 8.4
Note: percent by dry weight
Table 13. UPTAKE OF METALS BY PLANTS, COO’1 S PARADISE
(Reference 22)
MARSH, QNAJ
Species and Month Uptake ( n
dry weight)
Location Pb Zn
Cr Cd
LeTnna minor April 210.0 150.0
West Pond July 190.0 165.0
35.0 5.0
40.0 3.0
Leirria minor April 30.0 55.0
North Shore July 28.0 60.0
18.0 <1.0
23.0 <1.0
Myriophyllim vert April 30.0 40.0
West Pond July 45.0 36.0
Myrio yllinn vert April 20.0 30.0
North Shore uly 26.0 25.0
25.0 2.0
40.0 1.5.
12.0 <1.0
8.0 <1.0
clyceria grandis April 5.0 15.0
West Pond July 3.5 17.0
2.0 <1.0
2.5 <1.0
Glyceria grandis April 4.5 18.0
sjardins July 5.1 14.0
3.5 <1.0
2.5 <1.0
Glyceria grandis April 4.8 15.0
Long Valley July 5.0 14.0
2.0 <1.0
2.5 <1.0
21
-------
chromium, nickel, copper and zinc. An elevated level of nitro-
gen, phosphorus and organic carbon was found in the top 5 cm of
th bottom sediments. The authors conclude that the metals
found in the vegetation were extracted from the sediments,
which has been accumulating the metals Since 1919, not the
water column.
Fritz and Helle (Reference 12) have reviewed investigations
done on cypress strands and domes at the Center for Wetlands of
the University of Florida. Domes near the Whitney Mobile Home
Park receive 2.5 cm per week of secondary effluent and a 24 ha
portion of a very, large strand receives 450 Cu rn/day (0.12 mgd)
primary effluent from the town of Waldo, Florida. Removal of
nutrients, biochemical oxygen demand (BOD 5 ), suspended solids,
bacteria and heavy metals is accomplished by these cypress
wetlands. Table 14 contains nitrogen, phosphorus and BOD 5
data. The vegetation in the dome and the sediments act as
sinks for heavy metals; concentrations in dome waters are 2—3
times the influent. Trees grew 2.6 times faster in the dome
after the secondary effluent was applied than before. The
aquatic invertebrates and amphibians populations have decreased
with the effluent’s introductioxi. Fecal coliforms are com-
pletely removed by the domes. The survival and transmission of
viruses in the effluent as it passes through the, cypress dome
is presently being studied.
Table 14. CYPRESS DOME WATER QUALITY, WHITNEY MOBILE HOME
PARK, FL (Reference 12)
Criteria
Secondary
Effluent
Dome
Waters
Ground—
Waters
BOD 5 (mg/i)
About 40
About
20
—
Nitrogen
(mg—N/i)
8 — 15
8 —
15
0.1 — 2.5
Phosphorus
(mg/i)
8 — 13
.8 —
13
0.05— 2.0
Reedy Creek Utilities serves Walt Disney World in Orlando,
Florida (Reference 20). A mixed hardwood swamp of 41 ha has
been used to provide advanced secondary treatment and’ nitrogen
removal to an average of 7570 Cu rn/day (2 mgd) of secondary
effluent since July 1977. The bermed wetland area consists of
a thick understory (low to the ground growth, e.g. grasses,
22
-------
ferns) of vegetation and pine, cypress, and bay trees. A 91 cm
diamater pipe introduces the secondary effluent to the wetland
and the final discharge is through a 6 meter rectangular weir
after which the water flows ultimately to Reedy Creek. Bio-
chemical oxygen deinand,suspended solids, and total nitrogen
average 1 to 1.5 mg/i in the final effluent. Dissolved oxygen
is 1 to 2 mg/i in the final effluent. Color level is high due
to dissolved tannic acids from the decomposing organic matter.
Phosphorus may be diluted during periods of high flow because
of rain.
The town of Jasper, Florida, has discharged approximately
1136 cu rn/day (0.30 mgd) of wastewater into a very long cypress
strand for sixty years. Starting in 1920 the town discharged
raw wastewater, in 1950 they upgraded to ptimary treatment and
Since 1972 they have been discharging secondary effluent. A 28
ha section of this strand is being studied by Fritz and Belle
(personal communication) of Boyle Engineers. The study is to
determine appropriate loading rates for strand treatment. This
study is being accomplished under the sponsorship of the
National Science Foundation •and will be completed in 1981.
Full Scale Artificial Wetland Prolects
Sutherland and Bevis (Reference 29) have studied a seepage
(non—discharging) cattail wetlands of 465 ha which receives
643 cu rn/day (0.17 mgd) secondary effluent between June and
October, from the Town of Vermontvil].e, Michigan. Water
quality, flora and fauna have been studied. Table 15
summarizes water quality results. Vegetation biomass was
measured in standing crop, and nutrients levels in pounds per
acre contained in plant tissues were calculated. The amounts
of total phosphorus and total Kjeldahl nitrogen decreased in
successive units within the treatment train.
Demgen (Reference 8) and Bogaert et. al. (Reference 1)
studied an 8.1 ha (20 acres) marsh/pond wetland system at Mt.
View Sanitary District, in Contra Costa County, California.
The system has received 3028 cu rn/day (0.8 mgd) of secondary
effluent in six years. The goals of the system are both wild-
life habitat and effluent polishing. Water quality, biomass,
floral and faunal communities, and productivity have been re-
searched. The artifical wetland supports 72 species of plants,
22 species of animals, 90 species of birds, and 34 species of
aquatic invertebrates. Maximum standing crop bioinass of Typha
latifolia (cattail) and Scirpus californicus (bulrush) have
been •deterinined to be (as dry weight) 1872 g/sq In and 10,896
g/sq in, respectively. Table 16 lists water quality data.
There are seasonal variations which are not reflected in these
three—year averages. The additions of suspended solids and
biochemical oxygen demand are due primarily to algae growth.
23
-------
Table 15. WATER QUALITY IN SEEPAGE WETLANDS, VERMON’!IVILLE,
MIOIIGAN (mg/i) (Reference 29)
Criteria
Irifluent
Ponds
Wetland
Fields
Episodic
Overflc , ,
Ground-
water
Chlorides
280
207
157
123
124
Ammonia—
Nitrogen
37
2.5
2.0
-
—
0.7
Nitrate—
Nitrogen
1.3
1.0
1.2
—
1.4
TbtaJ. Kjeldahl
Nitrogen
81
6.5
5.0
—
3.7
ios tiorus
5.3
1.8
2.1
0.64
004
BOD 5
—
—
—
5.5
—
Sus nded
Solids
—
—
—
20
—
The Village of Neshaminy Falls, Pennsylvania, monitors
their marsh/pond/meadow treatment system to comply with NPDES
permit requirements. The monitoring began in May 1979 for
standard water quality parameters. The system has been in
continuous operation and has a final discharge. Tables 17 and
18 contain data showing levels of and removal rates for various
water quality parameters through each segment of the system.
The average daily level in the final effluent of dissolved
oxygen for 1980 was 6.7 mg/I. and for pH 7.5 units (personal
communication).
Table 19 contains a summary of the nutrient removal eff i—
ciencies achieved by full—scale wetland projects.
24
-------
Table 16. - MT. VIEW SANITARY DISTRICT WETLANfl WATER QUALITY
DATA, 1975—1978 (AV ) (ReferenCe- 1)
Wetland Wetland
Influent Distharge 1* Distharge 2* Percent R oova1
Criteria (mg/i) (mg/i) (mg/i) w.D.1 W.D.2
Nitrate Nitrogen 7.4 3.3 1.7 56 77
Amnonia Nitrogen 7.9 6.7 6.8 15 14
Organic Nitrogen 4.8 4.4 4.6 8 4
ios * ate
ios iorus 9.9 9.1 10 0.1 +1
Refractory
Organics** 50 33 36 34 28
BOD 5 23 24 15 +4 35
Suspended Solids 20 47 33 +135 +65
* See Figure 4, page 30 for location of wetland Discharge 1
and 2 (W.D.1 and W.D.2).
** Data represent only a one—year study
-
Table 17. NESHAMINY FALLS OP TIC AL RE. JLTS, WAI’ER JALITY
Average mg/i
Nklnber of Aeration
Parameter months Raw Lagoon Marsh Pond
sampled Influent Effluent Effluent Effluent
Final
Effluent
BOD 12 160 79 41 18
7
SS 20 171 182 45 27
11
Nrunonia—N 20 24 9 6 5
3
Nitrate—N 20 0.6 14 4 3
2
Total—P 15 8 8 3 2
2
25
-------
Table 18. NESRAMINY FALLS REMOVAL RATES
Parameter
Percent
Removal
By
Aeration
Lagoon
. By
Marsh
By
Pond
By
Meadow
Total
SOD
51
24
14
7
96
sS
6 increase
80
11
9
94
Ammonia—N
63
12
4
8
87
Total—P
0
63
12
0
75
DESIGN DATA FROM FULL SCALE WETLAND FACILITIES
A complete list of the full—scale wetland projects iden-
tified for this assessment is given in Table 20. Available
design data is summarized in Table 21 for each of the projects
and expanded descriptions follow for selected projects. Six of
the projects are briefly discussed including three natural and
three artificial treatment systems. The physical process,
design criteria, and equipment utilized in each project are
presented. Surface loading rates shown may be conservative due
to the availability of large tracts of marshes in some areas of
the country. The pilot projects now underway in Arcata,
California. Ontario, Canada and other areas will be valuable
in defining loading rates.
The Houghton Lake (Reference 16). peatland receives
secondary treated, dechlorinated domestic wastewater. The
wastewater is pumped through an underground force main from the
treatment plant to the edge of the peatland. At that point the
pipeline surfaces and runs along a çaised platform about 762
meters into the wetland. A second gated line, 975 meters long,
runs perpendicular. The water is evenly distributed over the
surface of the peat].and through 100 gates which discharge
approximately 60 liters/minute (16 gpm). Over 227,700 Cu m (60
mg) in 1978 and 3,875,000 Cu in (100 mg) in 1979 were discharged
to the wetland during the summer months. Surface water depths
are 2 to 8 cm and the water flows across the pea tland to the
lake.
26
-------
Table 19. JMMARY OF NtJ’ ID1T R.EI’VVAL TA 1 FULL SCALE WE’fl AND
a) Total dissolved tios iorus
b) Mnnonia nitrogen
c) Total nitrogen
d) Nitrate + Nitrite
e) May-Nov nber only
f) June-October only
Project
slow Wetland
m 3 /day Type 1DPa
Percent
Reduction
NH 3 .ND Nitrate
INC
Natural Wetland
Bri].].ion Marsh,
Wisconsin
757 Marsh 13
—
51
—
Houghton Lake,
Michigan
379 Peatland 95
71
99
Wildwood,
Florida
946 a amp/Marsh 98
—
—
90
Concord,
Massachusetts
2309 Marsh 47
58
20
—
Bellaire,
Michigan
1136 e Peatlarid 88
—
—
84
Cootes Paradise,
T ,n of Dondas
Ontario, Canada
— Marsh 80
—
—
60-70
Whithey Mobile
Home Park,
Florida
äpprox. Cypress Dome 91
227
•
—
—
89
Artificial Wetland
Vermontv ille,
Michigan
643 f Seeçege Marsh 95
72
Increased
—
Mt. View Sanitary
District,
California
Village of
NeshatninyFalls,
Pennsylvania
3028 Marsh/Pond 0
114 Marsh/Pond/Meadow 75
14
87
67
Increased
—
:
;
—
27
-------
TABLE 20. FULL SCALE WETLAND SYSTEMS IN THE UNITED STATES
a) Influent Types: 1. Aerated Raw Sewage; 2. Primary Effluent; 3. Secondary effluent
b) Effective removal area 3 ha
c) Effective treatment is achieved within 4 ha, but the total stand is approximately 160 ha.
d) May-November only
e) June-October only
Natural Wetlands
I\)
c
Project
Wetlands Type
Influent
ype
a
Wetland
Area
(ha)
Average Dry
Weather Flow
(m 3 /day)
City of Brillion, Wiséonsin
Marsh
-
3
1619*
757
.
Houghton Lake Sewer Authority, Mich.
Peatland
3
243 b
379
Whitney Mobile Home Park, Florida
Cypress dome
3
6*
227*
City of Wildwood, Florida
Swamp
2
202
946
City of Waldo, Florida
Cypress strand
2
l6O
454
Town of Drunuiiond, Wisconsin
Bog
3
10
379
Town of Concord, Massachusetts
Shrub, deep marsh
3
19
2,309
Hamilton Township, New Jersey
Freshwater tidal marsh
3
500
26,495
Town of Dundas, Ontario, Canada
Marsh
2
-
520
--
Village of Bellaire, Michigan
Forested
3
15
1 , 136 d
Reedy Creek Utilities, Florida
Swamp
Artificial Wetlands
3
41
7,570
Vermontville, Michigan
Cattail Marsh
3
4.65
643 e
Mt. View Sanitary District, Calif.
Marsh/pond
3
8.10
3,028
East Lansing, Michigan
Marsh/pond
3
15.80
1,892-3,785
Neshaminy Falls, Pennsylvania .
Marsh/pond/meadow
1
0.60
114
*Approxjmate ly
-------
TABLE 21.
DESIGN DATA FOR FULL-SCALE FACILITIES -- NATURAL WETLAND
a) Total marsh area
b) Study area
c) Depth kept below top of cypress
d) Treated effluent is discharged
knees
to stream above marsh
‘.O
.
Design Criteria
Brillion
Wisconsin
Houghton Lake
Michigan
Whitney Park
Florida
Wildwood
Florida
Drummond
Wisconsin
Wetland Type
Marsh
Peatland
Cypress/Duckweed
Swamp
Bog
Wetland Area (ha)
l6,l9 ’
156
243
2
6
202
24
Depth
Variable
uptoi5ni
2-8 cm
VariableC
-
--
20 cm
Substrate
Native soil
peat and clay
organic muck and
sandy clay
Underlaid by
native clay
Native clay
up to 11 m
organic
matter.
Flow (m 3 /day)
733—1533
379
approx. 227
946
379
Inlet structure
Streamd
Gated aluminum
irrigation pipe
Standpipe
Diversion
ditch
Gated irriga-
tion pipe
Surface loading
ha/l000 m 3 /day
b
101-212
b
5.3
26.4
214
63
Energy:
Pumping Requirements
To System
--
Yes
Yes
No
No
Within System
No
No
No
No
No
(Continued)
-------
Table 21 .Continued
Concord
Hamilton Marsh
Dundas
Bellaire
Reedy
Creek
Design_Criteria Massachusetts
New_Jersey
Ontario
Michigan
Florida
Wetland type Shrub/deep Ponds/marshes Marsh Forested •Swamp
marsh peatland
Wetland area (ha) 19 500 520 15 41
Depth Tidal Variable up Few inches Variable up
to 0.5 m variable to 1 meter
Substrates Organic silt Sand, silty Peat Native soils,
silt-clay clay, peat muck
Flow (m 3 /day) 2,309 26 , 495 e 1 , 136 f 7,570
Inlet structure 46 cm dis- Direct dis— 3—4 pipe 91 cm dis-
charge pipe charge to discharges charge pipe
tributary creek
Surface Loading
ha/I ,000 m 3 /day 8.2 1.9 13.2 5.4
Energy:
Pumping Requirements
To System No No - - No No
Within System No No No No No
e) Hamilton Marsh also received flow from other local streams in addition to the sewage effluent.
f) May-Novether only.
(Continued)
-------
Table 21. Continued
ARTIFICIAL WETLAND
Verrnontville Mt. View Sanitary Pleshaminy Falls
Design Criteria Michigan District, Calif. Pennsyvlania
Wetland Type Cattail marsh Marsh/ponds Marsh/pond/meadow
Wetlands Area (ha) 4.7 8.1 0.6
Depth (cm) 15 15-90
Substrate Clayey-silt Native clay Native clay mixed
with Bentonite and
compacted
Flow (m 3 /day) 643 3028 114
June-Oct only
Inlet Structure Multiple outlet Weir Overflow weirs
manifold pipe
Surface loading
ha/1000 m 3 /day 7.3 2.7 5.3
Energy:
Pumping Requirements
To System No No No
Within System No No No
-------
In the Whitney Mobile Home Park Project (Reference 12),
there are three process options Utilizing cypress wetland for
tertiary treatment. A dome is utilized in its natural state
and receives secondary effluent via a force main which extends
underground to the edge of the dome and then lays on top of the
organic layer inside the dome. The water is introduced to the
dome through a standpipe, so as not to disturb the organic
layer. The ponded wastewater percolates through the organic
muck and underlying sandy clay to the groundwater. There is
also an occasional spillover when the dome’s basin becomes
overloaded due to surface runoff. The isolated dome process is
the same as the natural dome except that it avoids this over-
flow problem. An earthen dike is constructed around the peri-
meter of the dome excluding any surface runoff. The third type
of cypress wetland is a strand. Secondary effluent is intro-
duced through a multiple inlet pipe along the upper end of the
strand and is conveyed in a sheet flow through it. Strands
may be up to several miles in length. The water passes
through various vegetation types: cypress, mixed hardwood, and
marshes. There may be channels and also ponded areas with
floating vegetation. It is a flow—through system.
The Hamilton Marsh treatment system (Reference 35) has a
simple process scheme. The treated effluent is discharged to
Crosswicks Creek above the marsh at a rate of 26,495 cu rn/day
(7 mgd). The effluent flows, with the water, to the marsh
where it passes through a number of habitat types —— streams,
high marsh, ponded areas that drain, and continuously wet
areas. There is a diversity of grasses and broad—leafed
plants. The flow is affected by the tides and eventually
reaches the Delaware River. No hardware is involved in this
system.
The Verxnontville, Michigan seepage wetland treatment
system (References 29 and 37) has been in operation since 1971.
The raw domestic wastewater is pretreated using a stabilization
pond. The water is then conveyed by gravity through a 10—inch
main and 8—inch manifold pipes having several outlets in each
of the three fields. Wastewater effluent is applied for 3—4
hours a day, 5 days a week from June to October. The water is
contained within these cattail wetlands until it seeps through
the soils to the lower plot. During heavy rains there is also
surface overflow from these upper wetlands to the lower plots.
The lower wetland normally only receives seepage and has a
surface discharge to a stream. Figure 3 shows the flow pattern
utilized in the Vermontville system.
32
-------
Wetland Field 1
Stabilization Pond
Wetland Field 2 - Wetland Field 4 Stream
Stabilization Pond 2 • Wetland Field 3
Figure 3. Vermontvile Michigan Seepage Wetland Pro ss Fl Diagram.
The Mt. View Sanitary District near Martinez, California
(Reference 7 and 8) has operated a system receiving 3,028
cu rn/day (0.8 mgd) of secondary treated domestic wastewater for
six years. The flow is by gravity and over weirs throughout
the system. Figure 4 shows the flow patterns.
Discharge 2
B • Receiving Stream
Secondary thannel
/ _____ ___ Discharge 1
A-i • A-2 ‘ - Receiving Stream
Figure 4. Mt • View nitary District Wetland Process Fl Diagr .
Plot D is channelized by .le vees with some growth of
emergent vegetation, primarily Typha . Plot E is open water
with islands, and Plot C is used seasonally for the growth of
grasses for migratory waterfowl food. Plots A—i and B contain
a high proportion of emergents, relative to surface area,
approximately 90 and 75 percent, respectively. Plot A—2 is
open water with artificial substrates in place of eme g.ent
vegetation and wind—operated circulators. The artificial sub-
strates are constructed of redwood bark to provide surface az’ea
for colonization by aquatic invertebrates and bacteria. There
is a continuous discharge from Plots A—2 and B.
Approximately 60 percent of the surface area is open water
allowing summer growth of algae. This creates large
differences in the discharge water quality. For example, the
four—year average effluent suspended solids concentration in
the winter was 24 mg/l while the summer average was 54 mg/i.
33
-------
The Village of Neshaininy Falls, Pennsylvania Utilizes a 0.6
ha meadow/pond/marsh system for its total domestic wastewater
treatment needs. The 114 cu rn/day flow is comminuted, mechani—
c l1y aerated, and flows to four parallel marsh plots, each 613
in’. The plots are sealed, filled with sand and planted with
cattails, The water passes through the root zone and overflows
to a two—meter deep facultative pond. After a 16—day detention
time, the water passes on to four parallel meadows, 306-sq in
each in area, which are planted with reed canary grass. The
final effluent is bhloririated and discharged into Little
Neshaminy Creek.
A partial list of full—scale projects presently in the
design phase is found in Table 22.
AVAIL LE EQUIPMENT AND HARDWARE
Products and suppliers of various equipment used in the
operation of various wetland systems are found in Table 23.
34
-------
TABLE 22. PARTIAL LIST OF FULL-SCALE PROJECTS IN
THE DESIGN PHASE (March 1982)
Location Contact Wetland Type Project Description
Black Diamond
Washington
Rick Esvelt
Kramer, Chin & Mayo
Seattle, WA
(206) 447-5359
Natural: Peat
bog overlain by
willows and
dense swamp plants
Nutrient removal from 1,250 m 3 /day
(0.33 mgd, annual average year 2000)
will be accomplished by the 46.5 ha
(115 acre) swamp. Begin construc-
tion 1981.
Vernon Township
New Jersey
James Hinckley
Consultant
25 Railroad Avenue
Warwick, NY 10990
(914) 986-3001
Artificial
meadow/rrarsh/
pond
System to treat wastewater from a
single townhouse development, design
flow 151 m 3 /day (40,000 gpd). Two-
thirds is secondary effluent, and
one-third is raw sewage. Begin
construction 1981.
LA) Brookhaven
0 1
New York
Maxwell. Small
Maxec, Inc.
Beilport, NY
(516) 286-8886
Artificial
marsh/pond
System being designed to treat
scavenger waste and leachate from
a landfill.
Eureka
California
Francesca Demgen
Demgen Aquatic Biology
Vallejo, CA
(707) 643-5889
Artifical
marsh
Marsh is specifically for habitat
creation. However, water quality
data will be collected and O&M data
will also be valuable. Marsh to
receive secondary effluent. Begin
construction 1982.
(Continued)
-------
TABLE 22. Continued
Location Contact Wetland Type Project Description
Savannah River
area between
Savannah and
Augusta, GA
M. Kristine Butera
National Aeronics &
Space Administration
Mississippi
(601) 688-3830
Pete Hodap Artificial
Engineers Assoc.
Fort Dodge, IA
(515) 576-7686
A waste stabilization lagoon and
borrow area, total 13 ha, will be
converted into an artificial wet-
land by seeding cattail and bul-
rush. The system will receive
2385 m 3 /day of secondary effluent.
Natural
Uorwalk
Iowa
This is a survey incorporating
Landsat (satellite) technology for
identification of and assessment
of wetlands for waste assimilation.
1 )
0 i
-------
Table 23. WAS’I!WATER WL’JLAND E JIPt4ENT su ’PL S
Product Description SuWlier
Wetland Vegetation Seeds and Rootstock Rester’ a Wild G ne
Food Nurseries, Inc.
P.O. Box V
Qnro, WI 54963
414/685—2929
Wetland Vegetation Seeds and Rootstock Wildlife Nurseries
P.O. Box 2724
Oskosh, WI 54903
414/231—3780
Ecofloats Artificial Pquatic PBC Cc nI ny
Invertebrate Habitat 222 Franklin Avenue
Wihits, CA 94590
707/459—6201
Windecos Unit canbining ecofloats EBC Can ny
and wind driven circulator (see above)
uascreena Screen for vegetation Menardi—Southern Corp.
control 3908 Colgate
Houston, TX 77087
713/643-6513
a) Aquascreen is not currently in use in wa.stewater wetlands, but is used
in o ther aquatic habitats. It has potential for use to control
vegetation growth in critical areas.
Other Notes -
1. Most equipment utilized in wastewater wetlands is standard and
suppliers will not be listed.
2. Construction of a wetlands may entail some tniiqjie problems. A light-
weight, wide track “Mud—Cat” bulldozer can be particularly useful on
soft soils.
37
-------
SECTION 4
TECHNOLOGY EVALUATION
PROCESS THEORY
Thtr oduct ion
The components of the wetland system which perform the
wastewater treatment are: algae, xnacrophytes (larger, rooted
plants), bacteria, zooplankton, and the substrate (bottom
soils). These components may be present in both natural and
artificial wetlands and no differentiation between these two
system types will be recognized in this section. The following
discussion of process theory will be subdivided into two
sections; the individual wetland components, and the removal
mechanisms for specific pollutants.
Wetland Components
The major system components affecting treatment of the
wastewater are: plants, soils, bacteria and animals. Also
influencing the treatment process are environmental conditions
such as pH, temperature, water depth, and dissolvedoxygen.
Each removal process requires specific conditions and the con-
duct of the process often induces changes in the original
conditions.
Plants——
The plant species present in a wetland system will vary
with the wetlands location and type. Table 24 lists some
dominant species in various wetland types. A wetlands system
will support the growth of a great variety of plant species,
the composition of which may change seasonally and over time.
The vegetation in wastewater wetlands experiences high levels
of productivity. Plants growing closest to the wastewater in—
fluent point often have elevated levels of chlorophyll a.
Plants, particularly algae, contribute oxygen to the water and
macrophytes influence evapotranspiration rates. This water
loss can be considerable in certain climates. Upon being
harvested, plants may be used for mulch, fertilizer, feeds, or
may be anaerobically digested to produce methane gas.
38
-------
TABLE 24. DOMINANT WETLAND PLANTS
Dominant Vege
Wetland Type Latin Name
tation
Common Name
Marsh
Phr&gmites
Reeds
Cattails
Buirushes
Typha spp.
Scirpus spp.
Cypress
Dome
Taxodium spp.
Lemna spp.
Cypress tree
Duckweed
Peatland
& x app.
Salix spp.
Chamae daphne calyculata
Betula pumila
Sedge
Willow
Leatberleaf
Bog Birch
Soils-•—
Wetland soils and sediment types are extremely variable.
Often, natural wetlands are underlain by a clay layer which
provides a natural seal. The sediments play a key role in
pollutant removal by supplying absorption sites for many
chemical constituents. Increased levels of clay particles and
organic matter in the sediments will allow increased absorption
of heavy metals and phosphorus. Bacteria and organic matter
will also collect on the sediment. This can create a layer
where anaerobic reactions will take place. The soil types
influence the amount of percolation in a non—sealed system. In
addition, the soil type affects vegetation able to grow in the
system.
Bacteria——
Bacteria serve to decompose organic matter and perform
many of the steps in the nitrogen cycle. A multitude of
bacterial species are present.
Animals--
In essence, the whole food web contributes to removal pf
pollutants in a wetlands treatment system. The larger animals
provide a mechanism for complete removal of some constituents
from the system. Zooplankton, the small free floating animals,
feed on algae and clumps of bacteria. Some of the aquatic
invertebrates also feed directly on this source and others
ingest zooplankton. The invertebrates and wetland plants serve
as food for a whole host of larger organisms: fish, birds,
reptiles, mammals, and amphibians. Wastewater wetlands can be
expected to attract many representatives of each animal
category.
39
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Removal Mechaniszq
The pollutant parameters to be discussed in this section
are: biochemical oxygen demand (BOD), suspended solids (SS),
bacteria and viruses, phosphorus, nitrogen, heavy metals, and
refractory organics.
Biochemical Oxygen Demand and Suspended Solids-—
BOD and SS introduced to t’he wetlands ecosystem are re-
moved through two basic processes. The long retention time and
low velocities allow a portion of the BOD and SS associated
with the heavier solids to physically settle and then decom-
pose. The soluble portion and lighter solids that will not
settle are metabolized by microorganisms within the water
column and on the surface of vegetation. These microorganisms
may include bacteria and zoop].ankton (cladocera, copepods and
rotifers).
Bacteria and Virus——
More is understood about the removal mechanisms affecting
bacteria than viruses. It is postulated that viruses are
absorbed by the soil as the water seeps through the sandy clay
soils under cypress domes. Viruses may also be deactivated
during retention in the wetlands because they are away from a
suitable host for too long. Bacteria are lost from the system
by sedimentation, ultraviolet radiation, chemical reactions,
natural dieoff and predation by zooplankton. Quantifying
bacterial removal rates are difficult when coliforins are used
as the test organism because animals living in the wetlands
contribute coliforxns. -
Phosphorus——
In many cases the primary purpose of a wetlands treatment
system is nutrient removal or conversion. The system’s ability
to meet this goal with respect to nitrogen is good, whereas
phosphorus removal is more variable. In the cypress domes and
Verxnontville seepage wetland, removal rates are high due to the
soil—water contact provided; the phosphorus is adsorbed onto
the soil particles. Peat also has this capability. In wet-
lands where the water only contacts a few centimeters of sub-
strate soils, the adsorption capacity is finite and may be
reached within the first few years of operation, depending on
the system size.
Plants supply other removal mechanisms. Duckweed, algae,
cypress trees and emergent vegetation such as cattails and
buirushes all assimilate inorganic phosphorus. The roots and
rhizomes of. the plants extract the phosphorus from the water.
Harvesting of the above ground vegetation biomass will
generally only remove ten percent’ or less of the phosphorus
applied to the system. Duckweed is an exception to this; when
40
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harvested it removes approximately two—thirds of the phosphorus
applied. High winter flows may cause flushing of the system’s
phosphorus contained within dormant and decaying plant parts.
Chemical precipitation by coinplexing with metals such as
iron and manganese is another method for phosphorus removal.
These precipitates are formed at high pH levels and under
aerobic conditions. They are released under low pH and anoxic
conditions; therefore, removal of phosphorus by this mechanism
may be temporary. It can be noted, however, that often the
phosphorus is complexed during the growing season and is re-
leased during the winter. In this case the receiving body may
not be as adversely affected by the phosphorus discharged as it
might be in warmer months.
Nitrogen—-
Nitrogen enters the wetlands in various forms: ammonia,
organic—N, nitrite, and nitrate. In cypress domes, duckweed
assimilates approximately one—half of the nitrogen applied. In
other marshes, algae and macrophytes incorporate ammonia and
nitrate. Much of this is a temporary form of removal unless
the plants are harvested. Harvesting can generally remove up
to only about 10 percent of the nitrogen added to the system.
Nitrification and denitrification result through bacterial
action. The former is accomplished in an aerobic atmosphere by
bacteria living on submerged surfaces such as plants, sediments
or artificial substrates. The end product of nitrification is
nitrate. In denitrification the nitrate is converted to N 2 0
and N 2 , gases which are lost to the atmosphere. This process
generally occurs in the sediments under low dissolved oxygen or
anaerobic conditions.
Volatilization provides another means of nitrogen removal
froic the system. In this process ammonia is lost to the atmos-
phere at a p greater than 8. Due to the availability of
nitrogen, fixation is not important in wastewater wetlands.
The process which contributes most to nitrogen removal depends
on the wetland’s characteristics. For example, the Houghton
Lake marsh was nutrient deficient prior to the introduction of
effluent. Therefore, the plants provide a great deal of re-
moval-by assimilating the nitrogen. A different method domi-
nates the Michigan State University ponds and wetlands. Here
high algae productivity elevates the pH to a point such that
volatilization takes place, thereby releasing ammonia to the
air during the warm summer months.
Heavy Metals——
The four mechanisms for removal -of heavy metals are 1)
formation of insoluble precipitates, 2) adsorption, 3) ion
exchange, and 4) assimilation. Insoluble precipitates of
metals such as lead, zinc, chromium, cadmium, nickel and copper
41
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can be formed. These precipitates may be formed with suif ides,
oxides, hydroxides, carbonates and phosphates. Adsorption and
ion exchange of the metals onto clay particles and with organic
compounds can Occur. Buirushes, reeds, cattails and duckweed
all have varying abilities to directly assimilate heavy metals.
These plants may concentrate the elements up to thousands of
times greater than the level in the surrounding water without
impairing their own functions. The variables affecting the
rate of removal for heavy metals include: the organic content
and cation exchange capacity of the wetland soil, salinity,
temperature, pH, sediment type, and vegetation type.
Refractory Organics——
There is some evidence showing that refractory organics
can be removed within wetland systems. Much study remains to
be done. Evidence suggests that phenolic compounds, chlori-
nated hydrocarbons, organic hydrocarbons and petroleum com-
pounds may be removed or broken down to some degree. The
investigations point to three methods for removal. Phenols and
perhaps other compounds can be metabolized by bulrushes to form
amino acids and proteins. The second mechanism is adsorption
to soil and plant surfaces and then chemical and bacterial
decay. Table 25 contains a summary of these removal
mechanisms. -
Constituent Removal Efficiencies——
In reviewing the literature dealing with wetlands, a great
deal of confusion exists in the reporting of performance data
for natural and artificial systems used for the treatment of
wastewater. Also, there is no standardization regarding the
basis on which performance data are reported. For example, in
some articles, performance data are reported as a function of
time, while in others as a function of distance. Usually, no
basis or information is given on how time or distance are
interrelated. Further, the data for most of the natural
systems are extremely site specific and should not be
general ized.
Recognizing the above limitations, the reported ranges of
removal for the constituents of concern in wastewater are
presented in Table 26. tFrom a review of the limited data
presented in Table 26, it can be concluded that the performance
of wetlands with respect to most wastewater constituents is not
well defined. Further, the range of values reported in Table
26 is also of concern, especially the lower removal
efficiencies.
42
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TABLE?5. CONTAMINANT REMOVAL MECHANISMS IN AQUATIC SYSTEMS
EMPLOYING PLANTS AND ANIMALSd (Reference 2 3)
Mechanism Contaminant Affectedb Description —
Physical
Sedimentation P - Settleable Solids Gravity settling of solids (and
- S — Colloidal Solids constituent contaminants) n pond/
I - BOD, Nitrogen, Phosphorus, marsh settings.
Heavy Metals, Refractory
Organics, Bacteria and Virus.
Filtration S - Settleable Solids, Colloidal Particulates filtered mechanically as
Solids water passes through substrate, root
masses, or fish.
Adsorption S - Co loidal Solids Interparticle attractive force (van
der Waals force).
Chemical
Precipitation P - Phosphorus, Heavy Metals Formation of or co—precipitation with
insoluble compounds.
Adsorption P - Phosphorus, Heavy Metals Adsorption on substrate and plant
S - Refractory Organics surface.
Decomposition P -Refractory’Organics Decomposition or alteration of less
stable compounds by phenomena such as
UV irradiation, oxidation, and reduction
(Continued)
-------
TABLE 25. (Continued)
Mechanism
Contaminant Affectedb
Description
Biological
.
Bacterial MetabolismC
P - Colloidal Solids, BOD, Nitro-
gen, Refractory Organics
Removal of colloidal solids and soluble
organics by suspended, benthic, and
plant-supported bacteria. Bacterial
ni tn fication/deni tn fication.
Plant Metabolismc
S - Refractory Organics, Bacteria
and Virus
Uptake and metabolism of organics by
plants. Root excretions may be toxic
to organismis of enteric origin.
Plant Absorption
S - Nitrogen, Phosphorus, Heavy
Metals, Refractory Organics
.
Under proper conditions, significant
quantities of these contaminants will
be taken up by plants.
Natiral Die-Off
P - Bacteria and Virus
Natural decay of organisms in an
unfavorable environment.
a Stowell, et al. Toward the Rational Design of Aquatic Treatment Systems . University of California,
Davis, 1980.
b P = primary effect; S = secondary effect; I = Incidental effect (effect occurring incidental to
removal of another contaminant).
C The term metabolism includes both biosynthesis and catabolic reactions.
-------
TABLE 26. REPORTED RANGES OF REMOVAL EFFICIENCY FOR WASTEWATER
CONSTITUENTS IN WASTEWATER IN NATURAL AND
ARTIFICIAL WETLAND (Based on Reference 31)
Removal Efficiency.
s
Natural
Wetlan&
Constituent Primary
Treatment
Secondary
Treatment
Primary
Treatment
Wetlan&
Secondary
Treatment
Total solids
40—75
Dissolved solids
5—20
Suspended solids
30—90
BOD 5
70—96
50—90
0—48
TOC
50—90
COD
50—80
50—90
Nitrogen (total as N) 90
40—90
30—98
Phosphorus (total as P) 84
10—61
20—90
0—60
Refractory organics
28—34
Heavy metalsa
20—100
Pathogens
PROCESS CAPABILITIES AND LIMITATIONS
Like all wastewater treatment systems,
specific capabilities and limitations. Some
bilities Or advantages include the following:
o Performance of the system is heavily dependent on the
proliferation of plants. These plants presently
exist in many areas of the country, allowing utili-
zation of wetlands nationwide.
o Operation and maintenance costs are generally well
below those of conventional treatment systems.
Removal efficiency varies with each metal.
wetland
of these
have
cap —
45
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o Wetland. can provide benefits in addition to Waste—
water treatment, such as wildlife habitat, open
space, recreation, education, and stream flow
augmentation.
o Treated ëf fluent from the wetlands can be available
for reuse and may be highly compatible for projects
involving aquaculture and silviculture.
o Many categories of pollutants are treated within a
single system.
o The treatment mechanisms (particularly the soil and
vegetation) are relatively stable, allowing the
system to withstand shock loadings.
Some of the limitations or disadvantages of wetland
treatment systems include the following:
o The amount of land required may prohibit their use in
highly urban areas.
o The treatment process efficiencies are not completely
defined, making precise design criteria difficult to
establish.
o The wetland plant species vary in their requirements
and may be limited by physical conditions such as
sunshine, temperature, and water depth.
o There is a possibility of vector breeding and
pathogen t-ransntission.
o Potential institutional problems may exist relating
- to obtaining discharge permits.
FULL SCALE DESIGN CONSIDERATIONS
Introduction
Specific design criteria for developing wetland wastewater
treatment systems are limited compared with conventional waste—
water treatment processes. In wetlands systems, removal eff i—
ciencies are a function of naturally occurring parameters which
cannot be easily controlled, such as temperature, sunlight, and
native plant species. This is unlike the flexibility enjoyed
in operating a conventional treatment plant. This difference
is one of the reasons that the design approach for wetlands is
much different than for that of conventional plants. Wetlands
technology does not lend itself to conventional design
criteria. This section will include information applicable to
46
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all types of systems with subsections for specific wetland
variations. Site specific information on sizing of pumps,
distribution lines, inlet and outlet structures will not be
included.
Wet1ai d TreMment System Design
There are several basic steps to be considered when
developing a preliminary design for a wetland treatment system.
Table 27 lists.these steps and is followed by a discussion of
each one.
TABLE 27. WETLAND DESIGN METHODOLOGY
1. Establish treatment goals based on:
a. Waste discharge requirements.
b. Reuse potential or concurrent beneficial use.
2. Evaluate land availability.
a. Existing wetland.
b. Selection of wetland types suitable with available
land.
- 3. Analysis of local conditions.
a. Water budgeting and application method.
b. Soils analysis.
4. Determine hydraulic loading and application method.
5. Select vegetation.
6. Design levees.
7. Design of distribution system to insure good circulation.
The first step in designing a wetland wastewater treat-
ment system is to establish treatment goals. The applicable
waste discharge requirements should be reviewed to determine
the level of treatment which is necessary. The possibility of
reuse of the wetland effluent should be considered as well as
concurrent beneficial uses of the wetlan d itself. Examples of
concurrent beneficial uses include: wildlife habitat,
education, recreation, aquaculture, irrigation and growing
vegetation for fuel for methane production.
Areas within an economically feasible radius of the waste—
water source should be surveyed to determine the availability
of natural wetlands or land for creation of an artificial
wetland. In choosing a natural system, the designer must
assess the existing uses of the wetland and the potential
environmental impacts of applying treated wastewater. If an
artificial system is to be designed then the type of system
must be chosen: marsh, marsh—pond, seepage wetland, or
47
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lined/vegetation trenches, etc. This decision is based upon
the availability and suitability of the land.
The third Step is to complete a water budget by analyzing
available wastewater flow, other poBsible inflows, precipi-
tation, percolation and evapotranspiration. Soils analyses are
necessary to assess the infiltration rate, suitability for
growing wetland vegetation, soil salinity, and amount of clays
and organic matter which will affect adsorption capacity. The
].ével of the groundwater table should be established and a
determination made as to whether the effluent will reach the
groundwater.
The results of the water budget allow calculation of
loading rates and total area requirements. Hydraulic loading
rates investigated or in use vary from 850 hectares per million
cubic meters of wastewater (8 acres/mgd) to hundreds of
thousands of hectares; therefore, practical considerations sUch
as available land area can influence the rate chosen. The
operating regime also may influence the land area required.
The wetlands may receive effluent year round or seasonally.
Wastewater may be applied on a continual or a batch basis with
a point or non—point discharge. Temperature restrictions
affecting growth of vegetation,, bacteria and other wetland
organisms will affect application rate and total area required.
In a natural wetland vegetation will already be present.
Some changes’iri species may be induced by the application of
wastewater. In an artificial wetland, vegetation will need to
be established. Vegetation selection is a key component in
design of an artificial system. The vegetation chosen will
have depth tolerance limits which should be incorporated into
the hydraulic scheme. Local varieties of cattail, buirushes,
reeds, and other emergents will be the most desirable. Some
may be planted by seed or rootstock and the others allowed to
colonize naturally. Care should be taken when selecttng exotic
(non—native) species. These non—natives could be detrimental
to the local environment beyond the bounds of the treatment
wetlands. By choosing native varieties of plants the designer
will be assured that the r are compatible with local weather
conditions. Vegetation should be planted in spring or early
summer and a full year allocated for start—up. A variety of
vegetation will usually become established in a stable environ-
ment.
Many wetland treatment systems incorporate levees within
the design. These levees should have steep side slopes,
usually 2:1, consistent with the soil characteristics. They
should be compacted and have two feet of freeboard. Top widths
should be eight to twelve feet and able to support a mainte-
nance vehicle. It is important to establish such access
48
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routes. For bogs and Cypress domes, boardwalks in lieu of
levees may be a more appropriate means of gaihing access.
vegetation will provide adequate erosion control except where
heavy stress conditions exist, such as around flow structures.
In these places additional erosion control measures should be
taken. The wetland treatment system perimeter may need to be
diked and perhaps fenced with a buffer zone between the treat-
ment system and non—treatment wetlands.
The necessity of maintaining adequate circulation is com-
mon to most of the wetland types except possibly cypress domes.
Influent and effluent structures should be placed so as to
avoid short circuiting. Multiple inlet structures may be
advisable. The effect of the prevailing winds should be con-
sidered. Natural and artificial islands, ditches and baffles
can also be used to influence flow patterns. The goals in
establishing good circulation are avoidance of stagnation and
short circuiting, and promotion of maximum vegetation/water
contact. The depth in most systems varies from 15 to 60 cm.
This allows good colonization by vegetation. In natural wet-
lands, such as bogs and other peatlands, the vegetation may be
several feet thick, although no open water is present.
Specific Wetland Types
Man—made and natural wetlands have both been used for
wastewater treatment. Man’ made or artificial wetlands have
been designed to be similar in appearance and species compo-
sition to natural wetlands. Marsh, marsh/pond and seepage
wetlands systems are in this category. Lined/vegetated
trenches are not of this type since each trench employs a
monoculture of vegetation and the system is not contiguous with
the surrounding environment. Natural wetland systems that have
been used in wastewater treatment include marshes, cypress
domes and strands, bogs and peat]ands. -
Artificial Marsh——
- Marshes may be located on historic tidelands, adjacent to
rivers or lakes, or completely removed from an existing body of
water. The artificial wetlands generally should be subdivided
into cells. The number of cells and their size depends on the
total project size and treatment objectives. Sufficient flow
structures should be designed into the system to provide for
alternate flow paths; flexibility is important. The depth
range is usually from 15 cm to 1 m.
Marsh/Pond——
The marsh/pond system is a combination of marsh areas and
shallow ponds. The ponds may have submerged vegetation, art-i—
ficial substrates or be totally open water. The artificial
substrates become colonized by bacteria, algae and aquatic
49
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invertebrates, thus serving as a partial substitute for emer-
gent vegetation in an open water environment. If the waste—
water is expected to have a high solids load it may be bene-
ficial to excavate a deep area close to the inlet to enhance
settling. This area could then be periodically dredged to
remove any excess build—up of solids.
Lined/vegetated Trenches--
Artificial wetlands can also be constructed in the form
of long, narrow trenches lined with clay or artifical membrane
and covered by gravel. Usually a single species of emergent
vegetation is planted in the trench (monoculture). The water
flows through the gravel—root zone.
Seepage Wetlands——
Seepage wetlands may be constructed on a number of soil
types. Table 28 lists the unified soil classes which have been
recommended as acceptable for establishing seepage wetlands.
Siltiness is a general indication of suitability. Most soils
within the five more suitable classes (ASTM standards) —— GM,
SM, SC, CL, and MH —— contain a significant portion of silt.
Mixtures of the finer sand grades and c]ayey sands within the
named soil classes may also be suitable 1 The mast desirable
range of hydraulic conductivity is lO to lO cm/sec. In
their natural condition, the forenamed classes could be too
permeable for wetland vegetation to establish itself. For
example, design for four inches per week a p ication would call
for hydraulic conductivity of around lO’ cm/sec, which is
close to the lower limit of infiltration indicated for the
first three classes named. However, the permeability of many
soils can be reduced during construction due to compaction.
Because compaction may decrease the soil’s water hydraulic
conductivity by an order of magnitu 3e or more, care in
achieving the. right degree of compaction is important. The GM,
SM, and SC soils may be readily compactible (fair to good
workability). The OL and MH materials are usually difficult to
work and to compact, and the OL soils may support only light
eguipment.
Natural Marshes——
In some cases, natural marshes may be used for treatmeht
of domestic wastewater with very few modifications. A levee to
enclose the area may be desirable, as might levees which divide
the area into sections. However, such subdivision has not been
incorporated in any existing full scale systems considered in
this study. As with other natural treatment systems, it is
generally advisable to carry out pilot studies prior to co in—
initting,a large wetland area to be used in wastewater treat-
ment. Establishment and monitoirng of appropriate control
areas is also generally advisable.
50
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TABLE 28. UNIFIED SOIL CLASSES AND HYDRAULIC CONDUCTIVITIES
(Reference 37)
ASTM
Soil
Class
Typical Names
Workability
Hydraulic
Conductivity 1O 3 to iO— 6 cm/sec -
.
GM
Silty gravels &
Gravel — sand — silt
Good
SM
Silty sands &
Sand silt mixtures
Fair
SC
Inorganic silts
Very fine sands
Silty or clayey. find sands
Clayey silts (low plasticity)
Fair
Hydraulic
Conductivity io— to io 6 cm/sec
OL
Organic silts
Organic silty clays
(Low plasticity)
Poor
ME
Inorganic silts
Micaceous or diatomaceous
Fine sandy or silty soils
Elastic silts
Poor
Artificial Wetland ——
Preliminary design criteria for some types of artificial
wetland have been developed by Tchobanoglous and Cuip
(Reference 31) who used data found in the literature. It is
presented in Table 29. The criteria presented are for the
application of primary or secondary effluent.
Cypress Domes, Strands or Swamps——
Cypress domes, strands, and swamps are different types of
southern wetlands dominated by cypress trees. The application
rate to cypress domes is generally 1.9 to 2.5 cm per week, to
allow for percolation. Often more than one dome will be
needed to accommodate the total wastewater flow. A cypress
strand is a flow—through system. These systems require a
holding pond having 3—14 day storage capacity to 1.) attenuate
51
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TABLE 29. PRELIMINARY’ DESIGN PARAMETERS FOR PLANNING
ARTIFICIAL WETLAND WASTEWATER TREATMENT SYSTEMSa
(Reference 31)
Type of
syst n
tharacter
istic/ sian r neter
Flow
regixTE
1 tention
time, days
E Ith of
flow, zn (ft)
Loading gate
ha/1000 m’/day
(acre/119i)
Range Typical
Range T ypi cal
Range Typical
Trench (with
reeds or rushes)
PF
6—15 10
0.3—0.5 0.4
(1.0—1.5) (1.3)
1.2—3.1 2.5
(11—29) (23)
Marsh (reeds
rushes, others)
AF
8—20 10
O.] 5—0.6 0.25
(0.5—2.0) (0.75)
1.2—12 4.1
(11—112) (38)
Marsh—pond
1. Marsh
AF
4—12 6
0.15—0.6 0.25
(0.5—2.0) (0.75)
0.65—8.2 2.5
(6.1—76.7) (23)
2. Pond
AF
6—12 8
0.5—1.0 0.6
(1.5—3.0) (2.0)
1.2—2.7 1.4
(11—25) (13)
Lined trench
PF
4—20 6
.
0.16—0.49 0.20
(1.5—4.6) (1.9)
%ased on the application of primary or secondary effluent.
bPF plug flow, AF = arbitrary flow.
peak loading; ‘2) settle gross suspended solids; and 3) provide
temporary storage for wetland maintenance. The water level
should be kept below the cypress tree knees. Permanent
flooding above the knees will kill the trees. It is important
during construction not t disturb the mucky organic sediments
in a cypress dome. This layer controls the slow percolation to
the ground water, thus avoiding its contamination. Cypress
domes have received wastewater through a stand pipe while
gated, aluminum irrigation header pipe with inlets every 15 to
30 m have generally been used in cypress strands. The dome’s
perimeter should be diked and perhaps fenced with a buffer zone
between the dome and swamp animal population.
Bogs and Peatlands——
Bogs and peatlands are sensitive ecosystems. It is
important that the method of introduction of the wastewater
does not disturb the vegetative mat. The distribution line may
be attached to a raised walkway which is anchored in the clay
52
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beneath the peatland. Distribution lines constructed of gated
aluminum irrigation header pipe or PVC have been used success-
fully. -
ENERGY ANALYSIS
One of the advantages of wetland systems is their lower
operational energy requirements compared with conventional
treatment plants. If the topography of the site allows gravity
flow from the treatment plant to the wetlands then there will
not be any operational energy demands except for those of the
maintenance vehicles. However, if gravity flow to the wetlands
is not feasible, pumping will be required, resulting in
additional energy demands. If the pumping demands are large,
energy requirements could approach those of a conventional.
treatment plant. -
The energy required by pumping is a function of wastewater
flow rate, the length of pipeline (the distance from the
treatment plant to the wetlands), the hours of operation, the
diameter of the pipe, and any static lift and dynamic head
losses.
All these variables could be combined in many different
combinations, and one combination cannot be singled out as a
“typical” example to evaluate. Instead, Figure 5 has been
prepared to enable the pumping energy requirements to be esti-
mated for a specific site. Each graph contains a family of
curves representing individual average daily flows. These four
graphs give the horsepower required to overcome friction losses
for different diameter pipes and distances between the treat-
ment plant and the wetlands. The calculated power required is
only for the friction losses in the pipe and does not include
any static lift.
Pumping may also be required to overcome any static lift
between the pretreatment effluent discharge and the wetlands
system inlet and to increase the head to insure quantity flow
through the wetland system. Figure 6 has been prepared to give
the horsepower required for different flow rates and static
lifts. This horsepower can be directly added to the friction—
loss horsepower to obtain the total horsepower required.
53
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I I I
80 /
Q:O.2mgd
60 //
— e’i. a.
V
40 /7
0 1 2 MI..ES
DISTANCE - TREAThENT PLANT TO WETLAtI
5
60
uJ
5
0
40
Mi
0
0.
Mi
I l )
0
0
0 1 2 MILES 4
DISTANCE - TREATMENT PLANT TO WETLAND
Figure 5. Power required to overcome friction loss,
for various flow rates (continued).
Mi
0
Mi
Mi
0
0.
Mi
0
0
I
/
/
___ —— 4 1n. dia.
6 1n. dIa.
— lOin. dia.
/
/
20
5
54
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30
• .
o
MILES
DISTANCE - TREATMENT PLANT TO WETLAND
3 4
MILES
DISTANCE - TREATMENT PLANT TO WETLAND
Figure 5. Continued
lOin. dia.
________ 12In. die..
— ___ 14 1n.-d la.
0—1.0 mgd
10
0
60
a
‘U
a
U i
‘U
0
‘U
a,
0
a
‘U
5
‘U
‘U
0
w20
C l,
0
I
12 1n.
_________ 14 1n.
—— 20 1n.
/
/
0—2.0 mgd
/
V
0
2
5
55
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5
0
LU
0
L i i
LU
02
3.
LU
U,
01
I
0
FIGURE 6. Static lift — power requirements.
The annual energy required (in kWh) can be calculated, by
multiplying the horsepower required, as determ ned from the
graphs, by the hours of operation expected per year, then
converting to kWh (1 hp = 0.747 kWh). An example problem using
Figures 5 and 6 follows:
Given: Flow = 3790 cu rn/day (1 mgd).
Distance between treatment plant and wetlands = 3.2 Km
(2 miles), 14 inch diameter pipe.
Difference in elevation between treatment discharge and
wetlands inlet = 2.13 in (7 ft).
Head required for gravity flow = 0.87 in (2 ft).
Pumps in operation 16 hours/day, 365 days/year.
Find: Energy required for pumping. I
Solution: First find the horsepower required to overcome the
- friction losses by using Figure 5. At 2 miles and f 1 or
a 14 inch pipe, the horsepower required is about 2.5
hp.
Next determine the power required to overcome the
static lift. The static lift would be the difference
in elevation (2.13 m) plus the head required (0.87 m)
or .3 m. From Figure 6, the horsepower required is 2.1
hp.
0 0.5 1 1.5 2
FLOW - MGD
56
-------
The total horsepower is 2.5 hp plus 2.1 hp or 4.6 hp.
The annual hours of operation are:
16 hr 365 days = 5840 hrs
day year year
The total annual energy required is:
5840 hrs 4.6 hp 0.7457kw = 20 000 kWh
year hp year -
It has been estimated that a 3,785 Cu in per day Cl ingd)
plant would require about 5700 liters (1,500 gal) a year of
gasoline for operating a maintenance vehicle. This voluzn of
gasoline has an equivalent energy value of l.58xl0° MJ
(44,000kWh) (Reference 30).
Energy consumption during construction also varies widely.
A natural wetlands may or may not require major constructed
modifications. The energy consumed during the construction of
a wetland is a function of the method of construction andthe
volume of earth moved. The amount of energy used can be esti—
mated from the energy construction costs and knowing the unit
cost of energy at the time of construction. The cost of energy
used is about 5 percent of the total construction cost.
OPERATION AND MAINTENANCE REQUIREMENTS OF WETLAND TREATMENT
SYSTEMS
Wetland treatment systems have low operation and
maintenance (O&M) requirements. Information is available for
some of the full scale projects. Tables 30 and 31 summarize
labor and O&M requirements.
Helle (personal communication) relates that there is no
daily maintenance requirements for c t press dome systems.
However, the distribution system may require daily checks if
pumps are involved. Every several years vegetation may need to
be planted or harvested and the subtrate examined.
Williams and Sutherland report that daily maintenance on
the Vermontville, MI seepage wetlands is restricted to seasonal
flow control. The other major maintenance activity is mowing
vegetation on the berms. There has been no substrate or vege-
tation maintenance activities necessary during the first six
years of operation. Three to four inches of organic debris has
accumulated in six years.
57
-------
TABLE 30.
LABOR FOR MAINTENANCE OF WETLAND TREATMENT SYSTEMS
Beilaire, MI N
4 15 1.1x10 6
200 13 l.8x10
Meadow/Mar sh/
Pond Eat iniate**
Vern ntvi1e, MI
Mt. View
Sanitary Dist.,
CA
A
A 6
* N = natural, A = Artificial
**R_ased on pilot work at Broo)thaven by nal1.
TABLE 31.
SUMMARY OF TYPICAL MAINTENANCE TASKS
Daily
Water Quality Monitoring
Flow Records and Meter Upkeep
Visual Inspeotion of Flow
Structures:
Weirs, Flumes,
Pipes, etc.
Periodic
Erosion Control
Levee Repair
Vegetation Harvest
Pumps Maintenance
Distribution Lines
Vehicles
Kadlec and Tilton give a detailed description of O&M
activities for the Bellaire, MI natural wetlands system. Flow
meters and water distribution and discharge structures need to
be checked daily. Levee maintenance and repair is crucial.
During winter and spring it occasionally becomes necessary to
cheTnicallyincreaSe the level of dissolved oxygen in the
Bellaire System. Sodium nitrate is added to the water to
accomplish this. This is the only chemical addition to a
wetland system mentioned in any of the literature reviewed for
this report. -
Syst n
‘Ikfpe* Years j
Service
Area
ha
Annual
1c ri
m-’/year
Operator
hours!
Year
Operator
hours!
ha/year
Operator
hours!
ai rn/yr
— 9.5Xl0 5 3120
4.65 9.5x10 4 400
8.1 1.]x10 6 1300
A 6
— 3.3x10 3
86 4.2x10 3
160 1.2x10 3
58
-------
Derngen describes the artificial wetlands at Mt. View
Sanitary District, CA which has been in operation six years.
The primary O&M activities are water quality monitoring, levee
repair and vegetation control. The monitoring effort is vari-
able. Levee repairs can be minimized through proper design.
Vegetation control depends on management goals. Vehicle and
flow structure repairs are periodic.
In a multi—cellular wetland treatment system, one of the
best management tools available is the ability to take a cell
out of service. This flexibility of flow paths allows the
wetlands manager to respond quickly to possible vector or
disease situations and also allows the performance of major
maintenance tasks. A cell could be flooded to permit fish
predation on mosquito larvae or drawn down to enable access to
a portion of a failing levee. The complete desiccation of a
cell would facilitate major repairs, design renovations or
vegetation control measures.
One of the major questions regarding wetland O&M is
vegetation control and harvesting. Of the thirteen full scale
projects investigated, none reported.major vegetation har-
vesting. In one artifical marsh project, vegetation control
measures have been taken, including deepening some channels to
prevent colonization. Floating harvesters were also tried on
the same project with little success, and only the tops of the
plants, not the roots, were removed, so regrowth was a possi-
bility. A major reason for harvesting vegetation is to resolve
a problem. Examples of possible vegetation induced problems
are: poor circulation yielding inefficient treatment, mosquito
breeding, and odors due to stagnation.
It is possible for wastewater wetlandS, as with most
natural wetlands, to emit odors. Some of the projects reported
that slight odors were created. Avoiding odors is accomplished
by maintaining aerobic conditions through circulation of water
within the system.
Vector production can be minimized through proper manage-
ment. Certain species of mosquitos may carry pathogens. The
wetland’s proximity to housing will determine the degree of
concern. A very successful management tool in controlling
mosquito larvae has been the introduction of Q busia app. ,
mosquito fish. Adequate circulation is important to minimize
stagnant conditions. -
Operations and maintenance tasks can be minimized through
proper design. O&M tasks can generally be accomplished by a
well trained operator. Often the time required is sporadic;
for example, two persons may be required for three full days
59
-------
for levee repair. However, such a task may not be required
again for many months. It is critical that a biologist
familiar with wetland habitats be available for consultation on
each project. This is due to the fact that both natural and
artificial wetlands are complex ecosystems.
COSTS
The costs of a wetland system can be divided into two
categories; construction (capital) and operation. Possible
costs incurred for construction include land acquisition, earth
work, artificial lining, pumps and piping and miscellaneous
equipment. The major operational costs include labor, mainte-
nance of equipment, energy if pumps are required, and moni-
toring. As previously emphasized, each system is unique and
therefore the cost will be variable.
Construction Cost
The largest construction expense for an artifical wetlands
is the earthwork. Earthwork consisting of excavation, back—
filling and dike construction at approximately $6.50 per cu m
($5/cu yd) was used for this report. Figures 7 and 8 give the
estimated cost for various earthwork volumes. Figure 7 is for
small scale projects, l0 g0O cu m or less and Figure 8 is for
large projects, up to 4x10 cu m.
The purchase price of the land can also be a major expense
in developing a wetland system. Since wetlands are land inten-
sive, it is important that the available land is reasonably
priced to keep the system cost—effective. Land cost vary
across the nation, ranging from $2470 to $4942 per ha ($1000—
2000 per acre) or higher. A reliable est.imate for a specific
site should be used when estimating land costs.
If a wetland system requires wastewater pumping, those
facilities must be included in the cost analysis. The
construction cost of a pump station has been estimated and is
presented on Figure 9 as a functionof the pumping capacity
(based on Reference 6). These costs include the pumps, the
structural housing and foundation. The pump station piping and
various appurtenances increase the cost an additional 30
percent over the values shown in Figure 9. This 30 percent
should be included in the total capital cost.
For systems which are not designed for seepage into the
soil, impermeable clay or artificial membrane liners may need
to be installed. Presently only the trench systems utilize
them. The costs of various membrane liners are found in Table
32.
60
-------
4
0
0
—
0
0
C
0
0
0
I-
F
0
0
0
I ,
C V)
C,)
C.)
C,
I L ’
I
20
0
: 16
C 12
Oc ’)
—o
—z
U i
S
I-
U)
0
C.)
8
4
0
8
VOLUME OF EARTHWORK, Thousand m 3
Figure 7. Cost of earthwork for small projects.
0 2 4 6
2 3 -
VOLUME OF EARTHWORK, M 11110 fl m 3
Figure 8. Cost of earthwork for large projects.
61
-------
,‘,
:
i
i
i
i
i
0.1 0.2 0.3 0.4 0.6 0.8 1 1.5 2
PUMPING CAPACITY mgd
Figure 9. Estimated construction cost of pump station.
Miscellaneous capital costs are common to all construction
projects. Costs specific to wetlands may include, but do not
necessarily require the following: the distribution system,
vegetation seeding, roads, sitework, fencing, lighting, instru-
mentation, and monitoring equipment. There are also the pro-
fessional fees for engineering design, biology consultants,
legal and administrative services. The individual cost of each
is relatively small compared to the total construction cost,
but combined they become a significant cost. The collective
rniscellaneous costs are usually estimated to be an additional
25—35 percent of the the construction cost. For a conservative
estimate the 35 percent value is used in this report. -
Operation and Maintenance Costs
The previous section discussed the normal tasks involved
in operating and maintaining a wetlands treatment system. !Ef
the system is designed properly, one of the largest operating
expense is labor. Labor estimates are based on the periodic
and routine tasks that are in the O&M schedule, and on the
surface area of land to be maintained. The operations require-
ments from actual experience listed in Table 30 do not corre-
late with the volume of flow or the wetland’s surface area.
Therefore, they are not used to make general estimates.
150
I-
a)
g- 100
e0
60
DC .)
40
ow
62
-------
TABLE 32. COST OF ARTIFICIAL MEMBRANE LINERS
I
Material
and Thickness
Fabricator (mu)
Expected
, life
(yrs)
.
Warranty
(yrs)
ost
5/rn 2
(S/ft 2 )
HYPALON-R
Globe—3 ply
Globe—5 ply
Watersaver
Staff
30
45
36
45
20
20
20
20
20
20
20
20
23 (0.65)
28 (0.80)
23 (0.65)
23 (0.65)
CPE-R
Watersaver
PALCO
Staff
36
36
——
10—20
10—20
——
none
none
none
21 (0.60)
16 (0.45)
21 (0.60)
PVC-
Watersaver
——
..
5
none
——
PVC-R -
PALJCO
20
3—5
none
12 (0.35)
NEOPRENE —
Watersaver
21
——
none
37 (1.05)
URETHANE -
Cooley, Inc.
——
?
none
——
PVC COt•IPOSITE -
Globe 6
Putterinan ——
10
•
.
10
59 (1.68)
aENR CCI 3384
Another operating expense hich has the potential of being
the major expense, is the environmental monitoring. Actual
costs will vary depending on the level, of monitoring required
by the NPDES permit. At the Vermontville Wetland, Michigan,
the environmental monitoring costs were 43 percent of the 1980—
81 Annual O&M Budget, and at Houghton Lake, Michigan, they were
53 percent in 1980 (Jeff Sutherland, personal communication).
Typical monitoring programs range between 20 and 50 percent of
the operating budget.
The O&M schedule is the most influencing factor in
evaluating the labor cost. For a specific wetlands, the annual
labor cost can be easily estimated once the O&M schedule has
been developed and the hourly rate of labor is known.
63
-------
When pumping is required, energy can be a costly item.
Specific costs can be estimated from the annual energy
requirements (in kwh) developed in the previous energy analysis
and by knowing the current electricity rate.
If an agency does not have a biologist on staff, a
consultant may be retained. Routine consultation will amount
to about 100 hours a year.
Miscellaneous costs include periodic repairs of levees,
maintenance of vehicles and equipment, energy, and general site
maintenance. As with the construction cost, the miscellaneous
costs can be estimated as a percent of the annual O &M budget.
A range of reasonable percentages should be based on actual
data. At this time operation of the existing wetland systems
is quite varied and reliable estimates can not be extrapolated.
However, an operator or engineer with experience will be able
to make reasonable estimates for a specific wetlandsystem once
the O&M schedule is defined.
64
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SECTION 5
COMPARISON WITH EQUIVALENT CONVENTIONAL TECHNOLOGY
INTRODUCTION
In Section 4, it was concluded that selecting an example
of a “typical t ’ wetland system would be too subjective and could
be misleading because of the many different wetland types, site
specific variables, and the lack of established design
criteria. However, in order to compare the wetlands systems
with conventional wastewater treatment technology, a range of
annual costs and energy demands for wetland systems was
developed. The values generated are conservative and for com-
parison purposes only.
To keep the comparison simple and representative, only one
type of wetlands was evaluated. An artificial wetland was
chosen rather than a natural one for two reasons. First, using
an artificial system will produce more conservative values
since more capital expenses are associated with the con-
struction of an artificial wetland. Second, estimating the
construction required to convert a natural wetland into a
wastewater treatment wetland is difficult since this is based
on site- specific conditions. Of the four prominent types of
artificial wetlands (Table 1), artificial marsh systems have
been selected because 1) they appear to have a large range of
application; 2) the four existing full scale artificial wet-
lands are or include marsh systems; and 3) there is more
available data on marsh systems than other wetland types.
The cost and energy requirements for a wetlands system
vary for different levels of treatment. Cost and energy
analyses were developed for three treatment levels; secondary,
advanced secondary and AWT. These three cases are defined
below. The removal rates are based on actual full scale re-
sults discussed in Section 3 and shown in Table 26. The sur-
face loading rates are from Table 29 which are based on the
full scale operations. The depth for all cases is 15 cm (0.5
ft).
65
-------
Treatment Quality
Case 1: Secondary Treatment
BOD 5 TSS N P
Influent (mg/i) 150 100 40 8
Effluent (mg/i) 30 30 29 6.4
Percent removed 80 70 30 20
Surface loading rate = 4 ha/1000 cu rn/day, 37 acre/mgd
Volume of excavation required = 6000 Cu m/1000 Cu rn/day
Case 2: Advanced Secondary Treatment
BOD 5 TSS N P
Influent (mg/i) 30 30 28 6.4
Effluent (mg/i) 15 15 11 2.6
Percent removed 50 50 60 60
Surface loading rate = 3.0 ha/l000..cu rn/day, 28 acre/mgd
Volume of excavation required = 4500 cu m/1000 Cu rn/day
Case 3: AWT
BOD 5 TSS _ N P
Influent (mg/i) 15 15 11 2.6
Effluent (mg/i) 8 8 4.3 1.1
Percent removed 50 50 60 60
Surface loading rate = 2.5 ha/1000 cu rn/day, 23.3 acre/mgd
Volume of excavation required = 3750 Cu rn/1000 Cu rn/day
Based on the above values, the total surface area require—
ir ents were computed and are shown in Table 33.
66
-------
TABLE 33. SURFACE AREA REQUIRED FOR MARSH WETLAND SYSTEM (IN
HECTARES)
Flow (Cu rn/day)
Case 1
Case 2
Case 3
400
1.6
1.2
1.0
800
3.2
2.4
2.0
2000
8.0
6.0
5.0
4000
16
12
10
8000
32
24
20
COST ANALYSIS
Cost estiniating procedures used in this report follow the
US EPA’S cost—effectiveness guidelines. Cost—effectiveness is
defined to include monetary cost and environmental and social
impact assessment. Capital cost estimates are based on the
Engineering News Record Construction Cost Index (ENR CCI) 20
cities average, March 1981. Capital costs are based on an
operable system with a 20—year life. If a system has an
expected service life of less than 20 years, the O&M cost
includes the annual present worth of subsequent replacement
required to obtain a 20—year service life. Salvage value for
estimated service life beyond 20 years is considered for land
and equipment as allowed by the EPA guidelines.
Capital costs include construction, engineering, legal,
administration and contigencies for all building, equipment and
appurtenances. Annual operation and maintenance costs include
labor, energy, chemicals and routine replacement of parts and
equipment (when replacement is required at intervals of five
years or less). Equipment cost estimates were based on
preliminary layouts and sizing, appropriate redundance,
quotations from equipment manufacturers and recent contract
bias as available. Operating cost escalations are projected to
be approximately 10 percent per year. The assumptions made for
the energy estimates in the previous energy section apply.
Basic cost assumptions include:
Service life = 20 years
Life cycle cost
interest rate (EPA required) = 7 percent
67
-------
Non—Component costs = piping @ 10%
Electrical @ 8%
Instrumentation @ 5%
Site preparation @ 5%
Total = 28% of
construction cost
Non—construction costs = Engineering and con-
struction supervision
@ 15%
Contingencies @ 15%
Total = 30% of
construction and non-
construction costs
Capital cost = Construction cost
plus non—component
and non—construction
costs
Capital recovery factor = 20 years, 0.09439
Present worth factor = 10.594 times
annual operating cost
ENR CCI (20 cities average
March, 1981) = 3384
Labor cost, rural community
( arch, 1981) = $11/hour
Energy cost (March, 1981)
Electricity (industrial
rate) = $0.11 MJ
($0.04/kilowatt hour)
Gasoline = $0.396/’ liter
($1.50/gallon)
Energy cost escalation factor
Electricity
1980—1990 28%
1990—2000 = 6%
Gasoline
1980—1990 = 34%
1990—2000 = 21%
As discussed in Section 4, capital costs include earth-
work, land acquisition, artificial lining, pumps and piping,
and miscellaneous equipment and costs. The operational costs
68
-------
include labor, maintenance of equipment, energy if pumps are
required and miscellaneous costs.
The major construction cost is earthwork which includes
excavation, grading, berm construction and compaction. The
estimated cost is $6.50/cu m ($5/cu yd). Table 34 shows the
estimated cost of earthwork, for various flows, for the three
cases.
TABLE 34. COST ESTIMATE OF EARTHWORK FOR MARSH WETLAND
SYSTEMS, IN THOUSANDS OF DOLLARS (ENR CCI 3384)
Flow(cu rn/day)
Case 1
Case 2
Case 3
400
15.7
11.7
9.7
800
31.3
23.3
19.7
2000
78.7
58.7
49.0
4000
157.0
117.0
9.7
8000
313.0
233.0
19.7
The cost of land varies across the country. A suggested
range is 52,470—4,942 per hectare (51,000—2,000 per acre)
(Referer ce 34). For this cost comparison, the value of $3,000
per hectare ($1,335 per acre) is used. Table 35 summarizes the
land acquisition cost for the three cases at various flows. A
cost sensitivity analysis indicates that land acquisition costs
may vary between 1. to 10 percent of the total present worth
cost - of the system.
In many cases, suitable wetland sites are already owned by
the municipality or by State and Federal agencies. These site
acquisition costs may not be significant for many projects.
TABLE 35. COST OF LAND ACQUISITION FOR MARSH WETLAND SYSTEMS,
IN THOUSANDS OF DOLLARS (ENR CCI 3384)
Flow (cu rn/day)
Case 1
Case 2 -
- Case 3
400
4.9
3.7
3.0
800
9.6
7.1
6.1
2000
24.0
18.1
15.0
4000
49.0
37.0
30.0
8000
96.0
71.0
60.0
69
-------
From the design data of full scale wetlands (Table 21),
it is observed, that only 3 of the 15 facilities require pumping
to the system and none of them require pumping within the
system. Since pumping is not common in full scale application,
pumps and costs associated with pumping will not be Considered
in this cost comparison.
All of the 15 full scale facilities use soil as a
substrate lining. Artificial liners appear not to be the
common practice and, therefore, will not be included in this
cost estimate.
A wetland system will usually require the use of a
utility vehicle. It is assumed that the municipality will
already own a vehicle for this purpose. Therefore, the capital
cost of the truck will not be included. An appropriate portion
of the vehicle’s maintenance and replacement cost will be
included in the wetland O&M budget.
The total capital cost including non—component and non—
construction costs for each case at the various flows is
summarized in Table 36. -
TABLE 36.. TOTAL CAPITAL COST FOR AN ARTIFICIAL MARSH WETLAND
SYSTEM, $ THOUSANDS (ENR CCI 3384)
Flow (Cu rn/day)
Case 1
Case 2
Case 3
400
34.3
25.63
21.1
800
68.1
50.59
42.9
2000
170.86
127.8
106.5
4000
342.8
256.1
211.4
8000
680.6
505.9
429.0
One of the largest O&M cost elements is the labor required
for the routine operation of the system. The actual labor
requirements experienced in full scale systems was presented in
Table 30 and they ranged from 86 to 160 operator hours/ha/year
for artificial wetlands systems. The rateof 160 o.h./ha/yr
will be used here for a conservative estimate. Table 37 shows
the expected labor requirements for the three cases at various
flows.
The utility vehicle O&M cost includes gasoline, routine
maintenance, and replacement cost. Reference 26 suggests 1500
liters of gasoline/bOO cu rn/day per year (1500 gal/ingd/year).
70
-------
TABLE 37. ANNUAL LABOR REQUIREMENTS FOR OPERATION AND
MAINTENMICE OF AN ARTIFICIAL MARSH WETLAND SYSTEM,
OPERATOR HOURS PER YEAR
Flow (Cu
rn/day)
Case 1
Case 2
Case 3
400
256
192
-
160
800
512
384
320
2000
1280
960
800
4000
2560
1920
1600
8000
5120
3840
3200
TABLE 38. ANNUAL O&M COSTS OF WETLAND UTILITY VEHICLE (ENR
CCI 3384)
FloW (Cu rn/day)
Cost
400
S
2,240
800
S
3,200
2000
S
5,000
4000
S
8,000
8000
$
14,000
The utility vehicle can be assumed to have an annual mainte-
nance cost of $1,000 and a replacement cost of $1,000/year.
The annual O&M cost of the vehicle is summarized in Table 38,
assuming a gasoline cost of $0.40/liter ($1.50/gal).
Since pumping is not included in this system, there will
not be any associated electrical cost. Miscellaneous cost,
including utilities, piping repair, and consultant biologist,
was estintated to be 15 percent of the annual O&M cost. As
mentioned previously, environmental monitoring can be a signi-
ficant expense. ‘or this cost analysis it was assumed that
environmental monitoring would be 30 percent of annual O&M cost
(including the above mentioned miscellaneous costs). Table 39
summarizes the total annual O&M costs. -
71
-------
TABLE 39. ANNUAL O&M COST FOR A MARSH WETLAND SYSTEM (ENR CCI
3384)
Flow (Cu rn/day)
Case 1
Case 2
Case 3
400
$ 7,500
$ 6,440
$ 5,910
800
$12,000
$ 9,870
‘
$ 8,830
2000
$41,100
$36,600
$20,000
4000
$48,100
$37,500
$32,200
8000
$91,400
$71,700
— $61,300
There are 15 situat ions (3 different cases and 5 different
flow rates) which could be analyzed. To keep this assessment
concise, only one flow rate will be used for the .3 cases
studied for the detailed cost analysis. The methodology used
for the cost estimate can be applied for any of the flow rates
and combination of cases. A flow rate of 4000 cu rn/day (1.06
mgd) has been chosen as the representative flow for small
communities. Other assumptions include:
o System is operating 12 months a year.
o Pumping is not required.
o Artificial liner is not required.
o Land costs are $3,000 per ha ($1,335 an acre).
o The salvage value of land is calculated by escalating
the purchase price by 1.806 (appreciation at a
compound interest rate of 3%/year for 20 years). The
present worth of the salvage value at the end of 20
years is that value multiplied by the single payment
present worth factor @ 7% for 20 years (0.2584).
The average annual cost for Case 1, primary effluent to
secondary, is $78,240, for Case 2, secondary effluent to
advanced secondary, is $59,980, and for Case 3, advanced
secondary effluent to AWT, is $50,280. The cost breakdowns are
presented for each case in Tables 40, 41 and 42.
72
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TABLE 40. ESTIMATED COSTS FOR A MARSH WETLAND SYSTEM, CASE 1,
4000 Cu rn/day, ENR CCI 3384
Item
Capital
Annual
O&M
Present
Worth
O&M
Total
Present
Worth
Average
Annual
Earthwork
$157,000
Land Acx ujsjtjon
49,000
Labor
—
$28,200
Utility Vehicle
—
2,000
Subtotal 1
206,000
30,200
Non-component
costs @ 28% 57,700
—
Misc. O&M @ 15%
—
4.500
Subtotal 2
263,700
34,700
Env ironTnental
Tronitoring
10,400
Non—construction
.
costs @ 30%
79 .100
Subtotal 3
342,800
45,100
$478,000
$821,000
$77,500
Energy:
gasoline
2,400
30,700
30.700
2.900
Subtotal 4
851,700
80,400
Land Salvage value
.
(subtract)
22.900
2.160
‘IOTAL
$828 ,800
73
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TABLE 41. ESTIMATED COSTS FOR A MARSH WETLAND SYSTEM, CASE 2, 4000 Cu
- tn/day, E R CCI 3384
Ite m
Capital
Annual
O&M
Present
Worth
O&M
Total
Present
Worth
-
Average
Annual
Earthwork
$117,000
Land Acquisition
37,000
Labor
—
$21,100
Utility Vehicle
—
2.000
Subtotal 1
154,000
23,100
Non—component
costs @ 28%
43,000
—
Misc. O&M @ 15%
—
3,500
Subtotal 2
197,000
26,600
Environmental
xTorlitoring
7,980
Non—construction
costs @ 30%
59.100
Subtotal 3
256,100
34,580
$366,000
$622,100
$58,700
Energy:
gasoline
2,400
30,600
30.600
2.900
Subtotal 4
652,700
61,600
Land Salvage value
(subtract)
17.300
1.630
‘jrJ j
$635.400
S59.980
74
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TPJBLE 42.. rIMATED COEIS FOR A MARSH WL’JLNID SYS’L M, C SE 3, 4000 o.i lu/day,
F R CCI 3384
Iten
Capital
Annual
0GM
Present
Worth
0GM
Total
Present
Worth
Average
Annual
rthwork $ 97,000
Land acx uisition
30,000
Labor
—
$
17,600
Utility Vehicle
—
2.000
Subtotal 1
Non—canponent
costs @ 28%
127,000
35,600
19,600
—
.
Misc. 0GM @ 15%
—
2.940
Subtotal 2
162,600
22,540
Enviror nenta1
•
Monitoring
.
6,750
Non—construction
costs @ 30%
48800
Subtotal 3
211,400
29,290
$310,000
$521,000
S
49,200
Energy:
gasoline
2,400
30,600
30.600
2.400
Subtotal 4
551,600
51,600
Land Salvageva1t
(subtract)
14.000
1.320
w’iw.
$537 .600
S
50.280
Cost Comparison
A range of average annual costs for conventional secondary
and advanced treatment systems were developed by completing a
present worth analysis of the cost data from the EPA Innovative
and Alternative Technology.Assess ent Manual (Reference 32).
These costs are the unit costs for various secondary and
advanced secondary treatment systems. The cost of treating the
influent (i.e. primary effluent or secondary effluent) is not
included. The cost of the following conventional secondary
treatment systems were included in the development of the cost
curves: activated sludge (mechanical aeration, high rate dif-
fused aeration, pure oxygen), trickling filters, rotating bio-
logical coritactors, and contact stabilization. The costs for
conventional systems include solid separation (i.e. clarifi-
cation) and sludge handling (i.e. dewatering, digestion, dis-
posal). The costs for the wetland systems do not include
sludge processing and disposal since it was assumed that sludge
75
-------
would not be removed from the systems. The cost of the
following processes were used for conventional advanced
secondary and AWT costs curves: dual media filters, activated
carbon, Phostrip, ion—exchange, break point chlorination’ and
ammonia stripping.
The range of costs are presented in two graphs, Figure 10
for secondary treatment and Figure 11 for advanced secondary
and AWT. These figures show the annual average cost as a
function of plant capacity for both the conventional and wet-
land systems. The ranges given for each system are based on
the cost estimate previously detailed.
Estimated savings, based in Figures 10 and 11, for
secondary and advanced waste treatment are shown in Table 43.
Since the annual costs for the conventional systems are
presented over a range, the mid—point cost for a given flow
rate was used for the comparison.
TABLE 43. COMPARISON BETWEEN WETLAND AND CONVENTIONAL SYSTEMS
ANNUAL AVERAGE COSTS (ENR CCI 3384)
Treatment Type (Cu
Flow
rates
rn/day) 400
2000
4000
8000
(mgd) 0.11
0.53
- 1.06
2.11
Secondary
.
Conventional
$28,000
$ 70,500
$111,000
$175,000
Wetlands (Case 1)
10,500
44,000
78,300
153,000
Savings
‘
17,500
63%
26,500
38%
32,700
29%
22,000
13%
Advanced Secondary &
AWT
Conventional
40,000
122,000
202,500
325,000
Wetlands (Case 2)’
8,700
29,000
60,100
116,000
savings
31,300
78%
93,000
76%
142,400
70%
209,000
64%
The calculated savings shown in Table 43 indicate that the
highest savings are realized at the lower flow rates and that
advanced wetland treatment provides more savings than secondary
wetland treatment systems. -
- The average annual cost can be divided into two com-
ponents: capital and annual O&M costs. Graphs for each of
these components were developed from Reference 32. Figure 12
shows the capital cost as a function of plant capacity for
76
-------
1000
500
100
50
10
5
PLANT CAPACITY -MGD
FIGURE 10. Average Annual Costs Comparison — Secondary Treatment.
0.1 0.5 1.0 5
10
0
0
C
0
I-
I-
C,)
0
U
-J
z
z
w
U i
>
77-
-------
PLANT CAPACITY - MOD
I
CONVENTIONAL
ADVANCED SECONDARY
AND AWT
— — — — — —
WETLAND
.........
WETLAND
AWT Case 3
FIGURE 11. Average Annual Cost Comparison — Advanced System.
0
0
V
3
0
I-
0)
0
0
-I
z
z
U i
a
Ui
>
500
100
50
10
5
0.1
0.5 1.0 5
10
ADVANCED SECONDARY - Case 2
78
-------
PLANT CAPACITY MOD
FIGURE 12.
Capital Costs Comparison.— Secondary System
5000
1000
500
100
50
0
0
0
0
0
C l )
I-
Cl)
0
a
-J
I-
a.
0
20
0.1
0.5 1.0 5
10
79
-------
secondary treatment, and Figure 13 for advanced and AWT
systems. These graphs show that the capital costs of wetlands
are significantly lower than the conventional Systems for all
three cases. Graphs showing the annual O&M cost as a function
of plant capacity are shown in Figures 14 and 15. Figure 14
presented the comparison for secondary treatment and Figure 15
advanced treatment figure 14 shows that the secondary wet-
land system’s O&M costs increase with flow more rapidly than
for conventional systems. For flows less than 3800 Cu rn/day
(1.0 mgd) the annual O&M cost of wetland systems are less than
or competitive to the conventional systems. As shown in Figure
15, the advanced wetland treatment system O&M costs are less
than the conventional systems.
ENERGY ANALYSIS
The only energy expended in the example marsh wetland
system is the gasoline used to operate the utility vehicle.
Table 44 lists the energy consumed by the vehicle, b sed on an
energy equivalent of 1.05x10 MJ per liter (l.27xl0 Btu per
gallon).
TABLE 44. ANNUAL ENERGY REQUIRED BY MARSH WETLAND SYSTEM
Flow
(Cu rn/day)
MJ/year x 108
‘Btu/yr
4d0
800
2000
4000
8000
0.63
1.27
3.16
6.32
12.7
2.Olx lO 7
4.04x10 7
l.01x10 8
. 2.01x10 8
4.04x 10 8
A range of energy requirements for conventional secondary
and advanced treatment systems were developed from the infcr—
mation in the EPA I/A Manual (Reference 32) and Reference 24.
The conventional secondary systems considered are activated
sludge, trickling filter, rotating biological contactors, a nd
contract stabilization. The conventional advanced and AWT
systems used for comparison are activated carbon, dual med ia
filters, nitrification, phostrip, ion exchange (for ammonia
removal) and ferric chloride addition. Again, these energy
requirements include solids removal (i.e. clarification) but
not sludge handling (i.e. dewatering, digestion, disposal).
Since the wetlands system consumes energy in the form of gaso-
line, the comparison between the wetlands and conventional
plants will be made in Btu’s. In converting the electrical kWh
demand into equivalent Btu’s, a conversion efficiency of 33
percent was used.
80
-------
5000
0.1 0.5 1.0 5
PLANT CAPACITY - MGD
10
:
CONVENTIONAL ADVANCED SECONDARY
AND AWT
WETLAND
ADVANCED SECONDARY
WETLAND AWT - Case 3
FIGURE 13. Capital Costs Comparison — Advanced System
C
0
0
C
C
0
I C
I-
U)
I-
U)
0
0
-l
I-
a.
0
1000
500
100
50
30
- Case2
81
-------
300
100
50
10
5
2
S
0
0
V
S
=
0
I C
I-
C l ,
I-
C l)
0
a
0
-I
z
z
FIGURE 14.
PLANT CAPACITY - MGD
10
Annual 0 & M Costs Comparison -Secondary Treatment.
—CONVENTIONAL
SECONDARY
0.1 0.5 1.0 5
82
-------
0.1 0.5 1.0 5 10
PLANT CAPACITY - MOD
FIGURE 15. Annual 0 & M CosteComparleon — Advanced Treatment.
1000
500
100
0
0
C
0
I-
U)
U)
.0
a
0
-a
z
z
50
10
5
3
83
-------
Figure 16 presents a graphical comparison between the
wetlands system and the conventional system. Estimated savings
for secondary and advanced treatment systems are shown in Table
45. Since a range of energy demands for the conventional
systems are presented in Figure 15, the mid—point energy value
for the selected flow rates will be used for the comparison.
As the comparison shows, there is considerable energy
savings (72 to 96 percent) with the use of wetlandB systems for
both secondary treatment and advanced treatment.
TABLE 45. COMPARISON BETWEEN WETLAND SYSTEMS AND CONVENTIONAL
SYSTEMS ANNUAL ENERGY REQUIREMENTS (Stu/yr)
Treatment Type
Flow rates (Cu rn/day)
8000
400
2000
4000
Secondary
Conventional
WetIan ds
Savings
3.9].x10 8
2.Olx].0 7
3.71x10 8
95%
1.56x10 9
1.01x10 8
1.46x10 9
94%
3.19x10 9
2.Olx]0 8
2.99x10 9
94%
1.07x10 °
4.04x]0 8
1.03x10 1 °
96%
Advanced
Conventional
Wetlands
Savings
7.75x].0 7
2.01x10 7
5.74x10 7
74%
3.85x10 8
1.OlxlO 8
2.84x10 8
74%
8.13x10 8
2.01x10 8
6.12x10 8
75%
l.52x10 9
4.04x10 8 .
1.1 x10 9
72%
84
-------
LEGEND
Advanced Secondary
Secondary
••se Wetland System
1.0
PLANT CAPACITY - MGD
FIGURE 16. Comparison of energy demands.
10,000
I-
z
0
-I
‘U
0
‘U
C
‘U
z
‘U
6,000
1,000
500
100
50
10
0.1
Conventional
0.6
5.0
85
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SECTION 6
NATIONAL IMPACT ASSESSMENT
POTENTIAL MARKET
A constructed (artificial) wetland system appears to have
greatest application for communities that have wastewater flows
of less than 7,570 cu rn/day (2 mgd). The flow limitations for
natural wetlands are dictated by their existing character-
istics. I
Climate is not a limiting factor, since wetlands can exist
in most parts of the Continental United States. The specific
wetland type is designed for and the plant species are selected
to adapt to the local climate. These vary across the nation.
For example, in Florida there are extensive areas of swamps,
cypress domes and strands , while in Wisconsin, Minnesota and
Michigan there are numerous bogs and peatlands
In most instances, a wetland will be treating waste from a
rural community rather than from a large urban community. This
is because wetlands are land intensive and are generally not
economical in major urban areas with high land costs.
The major potential market for wetlands system includes
communities with a flow of 7570 Cu rn/day (2 ingd)or less which
requires secondary, advanced secondary or advanced waste treat-
ment.
The EPA’S 1978 Needs Survey (Reference 33) estimated tne
number of secondary treatment plants and treatment plants 3e—
signed for more stringent treatment than secondary (advanced
secondary and tertiary facilities) which will need to be con-
structed between 1978 and 2000 (see Table 46).
COST AND ENERGY IMPACTS
Cost
The possible savings to be realized by the utilization of
wetland systems for secondary and advanced treatment is esti— -
mated by using the cost comparison graphs presented in Section
5. The approximate cost per plant was taken from the appro—
86
-------
TABLE 46. ESTIMATED TREATMENT PLANTS TO BE CONSTRUCTED BETWEEN
1978 AND 2000 (Reference 33)
Level of
Treatment
1—400
Total Projected
401—1900
Plow (iii 3 /day)
1910—4000
4001—7570
Secondary
2,790
1,089
169
52
Advanced
1,913
707
135
78
priate curve in Figures 10 and 11, at the higher end of the
flow range (e.g., at 400 cu rn/day for the 0 to 400 Cu rn/day
range) and at the midpoint of the cost range. For secondary
treatment, Case 1 was used, and for the advanced treatment,
Case 2 was used. Table 47 shows the saving calculation.
If 10 percent of all of the secondary plants, with a flow
less than 7570 Cu rn/day, that are anticipated to be constructed
in the next 20 years were wetlands rather than conventional
systems, the national cost savings in the year 2000 would be
about $11.3 million. As Table 47 shows, in the year 2000, the
total national savings related to the implementation of wet-
lands for all anticipated advanced treatment plants to be about
$17.2 million.
Energy
An analysis similar to that for cost has been completed
for the energy comparison. The approximate energy demand for
both the wetlands system and conventional plants were taken
from the energy comparison graph (Figure 15). Table 48 shows
the calculated savings.
If 10 percent of the anticipated secondary plants (with
flows below 7570 cu rn/day) to be constructed in the next 20
years were wetlands, 1 e average savings in energy consumption
would be about 2.79xl0 Btu/year or 93 percent of the conven-
tional plant usage. The savings expected from the impleinen—
tation of wetlands systems in the year 2000 for advanced
secondary and AWT at 10 percent of all anticipated plants (less
than 7570 Cu m/ 1 4 1 y) to be constructed in the next 20 years
would be 4.59x10& Btu/year, or 73 percent of the conventional
plant demand.
87
-------
TABLE 47. ESTIMATED ANNUAL AVERAGE COST OF 10 PERCENT OP THE
ANTICIPATED TREATMENT PLANTS, 1978-2000 (ENR CCI
3384)
Treatment
Type 0—400
Total Proj
401—1900
ected Flow
1910—4000
(Cu rn/day)
4001—7570 Total
Secondary
Conventional
Cost per plant $28,000
10% TOTAL u.s. 7.8]x10 6
$ 70 ’ 50 R
7,68x10
1.88x10
$l75,00
9.lxlO
1.83x10
Wetlands
Cost per plant 10,500
10% TOTAL U.S. 2.93x10 6
18,009
1.96x10°
78,30k
1.33x10
l53,00
7.96x10
7.02x10 6
Savings
(Conventional— 4.88x].0 6
Wetlands) 62%
5.72x10 6
74%
5.5x10 5
29%
l.14x10 5
13%
l.13x10 7
62%
Advanced Secondary and
AWT
Conventional
Cost per plant $40,000
10% TOTAL U.S. 7.65x10 6
$l22 00g
8.63x10
$202,50
2.73x10
$325,009
2.54xl0
$2.16x10 7
Wetlands
Cost per plant 8,700
10% TOTAL U.S. ].66x10 6
14,309
1.OlxlO°
60,109
8.13x1O
116,009
9.04xlO
4.39x10 6
Savings
(Conventicnal— 5.99x10 6
Wetlands) 78%
7.62x].0 6
88%
]..92x10 6
70%
l.64x10 6
64%
1.72x10 7
79%
PERSPECTIVE
Cost
The 1978 Needs Survey (Reference 33) estimates that about
$14 billion would be spent over the next 20 years in the United
States for secondary treatment facilities including new con-
struction, enlarging and upgrading existing plants. For plants
with capacity less than 8,000 Cu rn/day the estimated cost is
about $3.5 billion. The impact of the potential savings in the
year 2000 from installing wetlands are minimal (less than 5
percent).
88
-------
TABLE 48. ESTIMATED ANNUAL ENERGY DEMANDS FOR THE ANTICIPATED
- TREATMENT PLANTS, IN BTU/YEAR, 1978-2000
Treatment Total Projected Flow (cu mlday)
Level 0—400 401—1900 1910—4000 4001—7570
-
Total
Secondary
Conventional
per plant 3.9lx10 8 l.56x10 9 3.l9x10 9 1.07x10 1 °
10% Total
U.S. 8.54xl0 - 0 l.31x].O 1 4.l5x10 ° 4.28x10 10
3.Olxl& 1
Wetland
-
per plant 2.01x10 7 1.01x10 8 2.01x10 8 4.04x10 8
10% Total
U.S. 5.61x10 9 1.lOxlO 10 3.40x10 9 2.10x10 9
2.21x10 10
Savings
(Conven-
tional— 7.98x10 1 ° l.20x10 11 3.8lxl0’° 4.07x10 1 °
2.79x1& - 1
Wetlands)
93%
Advanced Secondary and AWT
Conventional 3.85x10 8 8.13x10 8 l.52xl0 9
per plant 7.75x10
10% Total
U.S. 1.2-5x10’ 0 2.31xl0 10 8.94x10 9 l.82xl0 °
6.27x1O °
Wetland
per plant 2.01x10 7 1.01x10 8 2.OlxlO 8 4.04xl0 8
10% Total
U.S. 3.85x10 9 7.14xl0 9 2.71xl0 9 3.15xl0 9
l.69x10 10
Savings
(Conven-
tional— 8.65x10 9 l.60x10 ° 6.12xl0 9 1.5lxl0 -°
4.59x].0 1 °
Wetlands)
73%
For advanced secondary treatment and AWT facilities (in-
cluding construction, enlarging and upgrading) the needs survey
estimates that $20 billion will be spent over the next 20
years. For plants with flows less than 8,000 Cu rn/day, the
estimate is about $4.9 billion. The impact of possible savings
in the year 2000 on the national budget for advanced treatment
are minimal.
89
-------
For bothsecondary and advanced treatment the estimated
national budget over the next 20 years is about $34 billion.
For those facilities with flows under 8,000 cu rn/day the esti-
mate is about $8.4 billion. The impact of possible savings in
the year 2000 on the national budget for secondary and advanced
treatment are minimal.
Energy
As reported in the EPA publication Energy Conservation in
Municipal Wastewater Treatment , (Reference 34) the 1990 esti-
mated energy consumption at public owned treatment worksf
secondary treatment is 216.51x10 Btu/year and 40.40x10
Btu/year for tertiary tre ment. The 1990 national energy use
is estimated to be 114x10 Btu/year.
The savings re. lized by using wetlands for secondary
treatment (2.79xl0 Btu/year) is about 0.13 percent of the
national energy required for secondary treatment i 1990. The
savings from advanced treatment wetlands (4. 5 9x101u Btu/year)
is 0.11 percent of the national tertiary treatment 1990 energy
budget. The savings realized by the use 11 of secondary and
advanced treatment wetland systems (3.25xl0 Btu/year as pre-
sented in Table 48) are insignificant (less than 0.01 percent)
to the total 1990 National Energy Use Budget. However, the
impact on a small local community may be significant.
MARKETABILITY/RISK
As previously discussed, the market for wetland systems
is limited in relation to the market for all wastewater treat-
ment facilities in the United States. This market is generally
limited to suburban and rural communities that have existing
natural wetlands or large areas of reasonably priced land, and
wastewater flows generally less than 7,570 cu rn/day (2 mgd).
However, the largest number of facilities needed are in this
range.
The marketability of wetland is dependent upon wetland
availability and the risk related to wetlands being a
relatively unproven wastewater treatment technology, and be-
cause it is a natural system. The risk is reduced with each
wetlands system that is implemented. As more performance data
are developed, the more refined and reliable the design
criteria becomes. Natural systems have the benefit of low O6M
costs, but there is also the drawbacks of the limited control
over the process. This risk may be reduced as design
parameters become more established and through additional
experiences with wetland systems.
90
-------
A community may justify the risk by taking into account
the favorable aspects of a wetlands system and the known risks
involved with conventional plants. The annual costs and energy
requirements of a wetlands system are considerably lower than
for conventional plants, which is probably the greatest incen-
tive for a small community.
91
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SECTION 7
LIST OF REFERENCES AND CONTACTS
1. Bogaert, Richard; Steve Breithaupt, Francesca Demgen. Mt.
View Sanitary District Special Marsh Studies,
Martinez, California, October 1980. In—house publi-
cation. P.O. Box 2366, Martinez, CA 94553.
2. Boyt, E. L.; S. E. Bayley, J. Zoltek, Jr. Removal of
Nutrients from Treated Municipal Wastewater by Wet-
land Vegetation . Journal of the Water Pollution
Control Association 49: 789—799. May 1977.
3. Cederguist, Norman. Suisun Marsh Management Study. Prog-
ress Report on the Feasibility of Using Waste Water
for Duck Club Management. U.S. Department of the
Interior, Sacramento, CA. September 1980 and July
1980.
4. Cederquist, Norman W. and E. Martin Roche. Reclamatjon
and Reuse of Wastewater in the Suisun Marsh,
California.” Proceedings: AWWA Water Reuse
Symposium, Washington, D.C. 1:685—702. 1979.
5. Crites, Ronald. tiEconomics of Aquatic Treatment Systems”,
in Aquaculture Systems for W j ater Treatment:
£ minar Proceedings S. C. Reed and R. K. Bastin, eds.
(EPA 430/9—80—006) MCD—67, U.S. Environmental Pro-
tection Agency, Washington, D.C. September 1979 pp.
475—4 85.
6. Culp, Wesner, Cuip. Process Deáign. -Performance ahd
Economic Analysis Handbook Biological Wastewater
Treatment Processes . For the Wastewater Treatinept
and Reuse Seminar, South Lake Tahoe, California,
October, 1977.
-7. Demgen, Francesca C. uWetlands Creation for Habitat and
Treatment —— At Mt. View Sanitary District, CA”.
in Aguaculture Systems for W .t ater Treatment:
minar Proceedings . S. C. Reed and R. K. Bastin,
eds. (EPA 430/9—80—006) MCD—67, U.S. Environmental
92
-------
Protection Agency, Washington, D.C. September 1979
pp. 61—73.
8. Demgen, Francesca C. and 1. Warren Nute. “Wetlands
Creation using Secondary Treated Wastewater”. Pro-
ceedings: AWWA Water Reuse Sympoisuin, Washington, D.
C. 1:727—739. - 1979.
9. De Jong, Joost. “The Purification of Wastewater with the
Aid of Rush or Reed Ponds”, Biological Control of
hater Pollution . 7. Tourbier and R. W. Pierson, Jr.,
eds. University of Pennsylvania, Philadelphia, Pa.
pp. 133—139. 1976.
30. Duffer, William R. and James E. Moyer. Municipal Waste—
water Ac uaculture . US Environmental Protection
Agency, Robert S. Kerr Environmental Research
Laboratory. Pub. No. EPA—600/2—78-].10. June 1978.
11. Fetter, C. W. Jr., W. E. Sloey and F. L. Spangler.
“Potential Replacement of Septic Tank Drain Fields by
Artificial Marsh •Wastewater- Treatment Systems”,
Groundwater . 14:6:396—402, November—December 1977.
12. Fritz, Walter R. and Steven C. Helle. Final Report:
Tertiary Treatment of Wastewater Using Cypress Wet —
lands. Boyle Engineering Corporation, 3025 East
South Street, Orlando, FL 32803. December 1978.
13. Gearheart, Robert, et al. “Second Quarterly Report —
First Year City of Arcata Marsh Pilot Project” Pro-
ject No. C—06—2270. Department of Public Works,
Arcata, California. April 1981.
14. Gosselink, James C., Eugene P. Odum, R. M. Pope. The
lue of the Tidal marsh. Center for Wetland Re-
sources, Publication No. LSU—SG—74--03. Louisiana
State University, Baton Rouge, LA 70803. May 1974.
15. Kadlec, Robert H. and Donald L. Tilton. N nitoring Re
port on the Bellaire Wastewater Treatment Facility .
University of Michigan Wetlands Ecosystem Research
Group, Ann Arbor, MI 48109. Utilization Report No.
1, August 1977; Utilization Report No. 2, March 1978;
Utilization Report No. 3, January 1979.
16. Kad].ec, Robert H., Donald L. Tilton, Benedict R. Sch—
wegler. Wetlands for Tertiary Treatment: A Three—
Year Summary of Pilot Scale Operations at ‘Houghton
Lake . University of Michigan Wetlands Ecosystem
Research Group, Ann Arbor, MI. February 1979. -
93
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17. Kappel, WIn. N. “The Drummond Project —— Applying Lagoon
Sewage Effluent to a Bog: An Operational Trial” in
Aguaculture Systems for Wastewater Treatment: Semi-
nar Proceedings . S. C. Reed and R. K. Bastin, eds.
(EPA 430/9—80—006) MCD—67, U.S. Environmental Pro-
tection Agency, Washington, D.C. September 1979 pp.
83—90.
18. King, Darrell L. and Thomas M. Burton. “A Combination of
Aquatic and Terrestrial Ecosystems for Maximal Reuse
of Domestic Wastewater”. Proceedings: AWWA Water
Reuse Symposium, Washington D.C. 1:714—726, 1979.
19. Klopp, Frank R. and Robert A. Gearheart. City of Arcata
Proposal for a Marsh Wastewater Treatment and Recla—
niation Project. Arcata, California. June 1979.
20. Kohl, Robert H. and Ted McKim. “Nitrogen and Phosphorus
Reduction from Land Application Systems at the Walt
Disney World Resort Complex”, International Seminar
on Control of Nutrients in Municipal Wastewater
Effluents. Proceedings Volume III: Nitrogen and
Phosphorus. September 1980, page 118.
21. Lakshman, G. “An Ecosystems Approach to the Treatment of
Wastewaters, Journal of Environmental Ouality ,
8:3:353—361. 1979.
22. Mudroch, A. and J. A. Capobianco. “Effects of Treated
Effluent on a Natural Marsh”, Journal of the
iQn_n:2J._ Ati D ,. Sept em be r 1979,
51:2243—2256.
23. Nute, J. Warren. “Marsh/Forest Demonstration Project
Feasibility Assessment.” August 1979. J. Warren
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24. Roberts, Edwin and Robert Magan. Guidelines for the
Estimation of Total Energy Requirements of Municipal
k astewater Treatment Alternatives . A report to the
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the University of California at Davis, August 1977.
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NH. August 1978.
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Aquatic. Treatment Systems”. Department of Civil
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CONTACTS
GENERAL
William R. Duffer, Ph.D.
US EPA
Robert S. Kerr Environmental
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P.O. Box 1198
Ada, OK 74820
(405) 332—8800
PILOT AND FULL SCALE FACILITIES
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University of Wisconsin/Oshkosh
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IEP
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Robert K. Bastian
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Mrs. A]ena Mudroch
Environmental Contazuients
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Biology Department
Rider College
Lawrenceville, NJ
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Dept of Chemical Engineering
University of Michigan
Ann Arbor, MI 48109
(313) 764—3362
08648
97
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Mt. View, S.D., CA:
FranCesCa Demgen
Demgefl AqUatiC Biology
118 MississipPi Street
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Président
A.W. Martin Asso, Inc
P.O. Box 190
King of Prussia, PA 19406
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Mr. Robert Kohl
Reedy Creek Utilities
P.O. Box 40
Lake Buena Vista, FL 32830
(305) 824—4026
switchboard (305) 824—2222
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do Williams & Works, Inc.
611 Cascade West Parkway
Grand Rapids, MI 49506
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School of Forestry Resources
& Conservation
University of Florida
Gainesville, FL 32611
(904) 392—1850
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Department of Environmental
Engineering Science
University of Florida
Gainesville, FL 32611
(904) 392—0841
Co., Inc
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