&EPA
United States
Environmental Protection
Agency
Graywater Treatment Using Constructed Wetlands
Office of Research and Development
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EPA/600/R-12/684
October 2012
Graywater Treatment Using Constructed Wetlands
by
Adam Jokerst1, Meg Hollowed1, Sybil Sharvelle1, Larry Roesner (retired)1, A. Charles Rowney"
'The Urban Water Center
Department of Civil and Environmental Engineering
Colorado State University
Fort Collins, CO 80521-1372
2ACR, LLC
Longwood, Florida, 32750
Contract No. 8C-R056NTSX
Project Officer
Thomas P. O'Connor
Technical Advisor
Richard Field (retired)
Urban Watershed Management Branch
Water Supply & Water Resources Division
National Risk Management Research Laboratory
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OH 45268
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Notice
The U.S. Environmental Protection Agency, through its Office of Research and Development, funded and managed,
or partially funded and collaborated in, the research described herein. It has been subjected to the Agency's peer and
administrative review and has been approved for publication. Any opinions expressed in this report are those of the
authors and do not necessarily reflect the views of the Agency, therefore, no official endorsement should be inferred.
Any mention of trade names or commercial products does not constitute endorsement or recommendation for use.
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Abstract
Mounting pressure to conserve water resources has prompted the notion that the separation of graywater from
sewerage through the use of dual-plumbed systems may enable graywater to be reused at the household level for such
non-potable demands as landscape irrigation or toilet flushing. Although graywater reuse holds great promise as a
means to reduce potable water demands, water quality and health concerns arising from the level of contamination
typically found in graywater have impeded the practice from gaining wide-scale application in the United States.
Simple treatment schemes, such as those using constructed wetlands, could reduce graywater pollution and allow for
expanded reuse applications. This report documents the results of a study examining the treatment efficiency of a
pilot-scale constructed wetland system for graywater over a one-year period, and explores the potential for onsite
reuse of the treated effluent for outdoor irrigation. The wide range of measurements taken, including those of anionic
surfactants and of indicator microorganisms, provides a comprehensive assessment of the treatment efficiency and
outflow water quality characteristics of such systems.
Results of water quality measurements indicated that the constructed wetland substantially reduced organics, solids,
nutrients, pathogens, and surfactants throughout the one-year sampling period. In particular, removal rates of
biochemical oxygen demand and total suspended solids averaged 91% and 77% respectively, while removal of
anionic surfactants averaged 94% and never dropped below seasonal mean of 88% throughout the year. The wetland
reduced pathogenic indicator microorganism concentrations by approximately two orders of magnitude on average,
producing effluent concentrations below primary contact standards for all seasons except winter. A comparison of the
wetland effluent quality with state reclaimed water quality regulations indicated that effluent would typically meet
reclaimed water quality standards for restricted irrigation reuse. However, treatment efficiencies decreased
precipitously during winter months, producing an effluent likely unsuitable for unrestricted reuse.
in
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Contents
Notice ii
Abstract iii
Contents iv
List of Figures vi
Acronyms and Abbreviations viii
Acknowledgements ix
Executive Summary 1
Chapter 1 Introduction 3
Overview 3
Objectives 4
Chapter 2 Conclusions and Recommendations 5
Wetland Performance 5
Public Acceptance 6
Recommendations for Future Study 6
Chapter3 Background 7
Graywater Definition, Quantity, and Reuse Savings 7
Graywater Quality 7
Applicable Water Quality Standards 9
Constructed Wetlands 11
Chapter 4 Materials and Methods 13
Wetland Configuration 13
Graywater Sources 17
Flow Monitoring 20
Water Quality Analysis 22
Analysis Methods 23
Chapter 5 Wetland Performance 25
Treatment Efficiency Determination 25
Hydrologic Performance 26
Water Quality Results 28
Water Quality Statistical Analysis 47
Chapter 6 References 51
Appendix A Data 1
Precipitation Record 1
Flow Data 1
Water Quality Data 9
iv
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List of Figures
Figure 4-1. Graywater wetland location and layout. (Aerial photo © DigitalGlobe, 2009) 14
Figure 4-2. Graywater wetland configuration 14
Figure 4-3. Freshwater surface wetland spring 2009 15
Figure 4-4. Freshwater surface wetland fall 2009 15
Figure 4-5. Subsurface wetland spring 2009 16
Figure 4-6. Subsurface wetland fall 2009 16
Figure 4-7. Graywater storage tank, pump, and piping system used to collect graywater from the dormitory 18
Figure 4-8. Trailer-mounted tank used to haul dormitory graywater to the wetland system 19
Figure 4-9. Metering pump in insulated box used to transfer dormitory graywater from trailer-mounted tank to
wetland system 19
Figure 4-10. Flow meter design 21
Figure 4-11. Water quality sampling locations 22
Figure 5-1. Seasonal averaged flow rates in the wetland system 27
Figure 5-2 Plotted box plots for specific conductivity 29
Figure 5-3 Plotted box plots for turbidity 29
Figure 5-4. Plotted box plots for biochemical oxygen demand 32
Figure 5-5. Plotted box plots for total organic carbon 32
Figure 5-6. Percent organic removal efficiencies 33
Figure 5-7. Plotted box plots for total nitrogen 34
Figure 5-8. Plotted box plots for ammonia 35
Figure 5-9. Percent nitrogen removal efficiencies 36
Figure 5-10. Plotted box plots for total phosphorus 37
Figure 5-11. Plotted box plots for phosphate 38
Figure 5-12. Percent phosphorus removal efficiencies 39
Figure 5-13. Plotted box plots for total suspended solids 40
Figure 5-14. Plotted box plots for total dissolved solids 41
Figure 5-15. Plotted box plots for total volatile solids 42
Figure 5-16. Percent suspended, dissolved, and volatile removal efficiencies 43
Figure 5-17. Plotted box plots for anionic surfactants as LAS 45
Figure 5-18. Percent anionic surfactant removal efficiencies 45
Figure 5-19. Single sample Escherichia coll log concentrations 46
Figure 5-20. Escherichia coli mean removals by log concentrations 47
Figure-1. Precipitation record during the sampling period 1
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List of Tables
Table 3-1. Graywater Quality Characteristics from Literature 8
Table 3-2. Microbial Quality of Graywater 9
Table 3 -3. State Reclaimed Water Quality Standards for Unrestricted Urban Reuse (EPA, 2004) 10
Table 3-4. Pathogen Indicator Limits for Primary Contact in Freshwater (EPA, 1986) 10
Table 4-1. Porosity Determination of the Subsurface Flow Wetland 16
Table 5-1 Seasonal Mean Flow Rates and Standard Deviations 26
Table 5-2. Seasonal Mean Hydraulic Retention Times and Standard Deviations 28
Table 5-3. Seasonal Mean Physio-chemical Parameters Measured in the Greywater Wetland 30
Table 5-4. Recommended Specific Conductivity Levels (FCES, 2004) 31
Table 5-5 Chloride and Sulfate Measurements and Statistics 44
Table 5-6. Water Quality Statistics for All Data Collected 48
Table-1. Flow Rates, Ice Thicknesses and Volumes 2
Table-2. Fall Graywater Quality Data 10
Table-3. Winter and Spring Graywater Quality Data 12
Table-4. Summer Graywater Quality Data 14
VI
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Acronyms and Abbreviations
ABS
ACB
APHA
ANOVA
BDL
BMP
BOD
CoAgMet
CDPHE
cr
csu
DO
DOC
DTN
E. coll
EPA
ES
FCES
FWS
HOPE
HRT
IBR
I/I
LAS
MBAS
MBR
MF
NH3
NO3
ORD
O&M
PO43
PVC
QAPP
QA/QC
SC
SF
SM
SO42
Temp
Alkyl benzene sulfonate
Atmospheric Chemistry Building
American Public Health Association
Analysis of Variance
Below detection limit
Best Management Practice
Biochemical oxygen demand
Colorado Agricultural Meteorological Network
Colorado Department of Public Health and Environment
Chloride
Colorado State University
Dissolved oxygen
Dissolved organic carbon
Dissolved total nitrogen
Escherichia coll
Environmental Protection Agency
Enzyme substrate
Florida Cooperative Extension Service
Free water surface wetland
High density polyethylene
Hydraulic retention time
Increasing block rate
Inflow/infiltration
Linear alkyl benzene sulfonate
Methylene blue active substances
Membrane bioreactor
Membrane filtration
Ammonia
Nitrate
Office of Research and Development
Operation and maintenance
Phosphate
Polyvinyl chloride
Quality assurance project plan
Quality assurance/quality control
Specific conductivity
Subsurface flow wetland
Standard Methods
Sulfate
Temperature
vn
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TDS Total dissolved solid
TN Total nitrogen
TOC Total organic carbon
TP Total phosphorus
TS Total solids
TSS Total suspended solid
TVS Total volatile solid
U.S. United States
VSS Volatile suspended solid
WWF Wet-weather Flows
WWTP Wastewater treatment plant
s standard of deviation
Vlll
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Acknowledgements
An undertaking of this type requires the dedication and cooperation of a team. The technical direction and
coordination for this project was provided by the technical project team of the Urban Watershed Management Branch
(UWMB), under the direction of Mr. Thomas P. O'Connor, the Project Officer and Mr. Richard Field, the Technical
Advisor (retired). Ms. Carolyn Esposito of UWMB reviewed the quality assurance project plan and the report as well.
Mr. Anthony Tafuri of UWMB, Mr. Robert Goo of EPA's Office of Water, and Dr. Francis Digiano of the University
of North Carolina provided technical reviews. Yongdeok Cho contributed to early versions of the design of the
constructed wetlands. Finally, the contributions of the many authors and professionals who were contacted or cited in
this work are acknowledged, as it is their efforts that underlay the discussion and advances contained in the report.
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Executive Summary
Mounting pressure to conserve water resources has prompted the notion that the separation of graywater from sewer
effluents through the use of dual-plumbed systems may enable graywater to be reused at the household level for such
non-potable demands as landscape irrigation or toilet flushing. Although graywater reuse holds great promise as a
means to reduce potable water demands, water quality and health concerns arising from the level of contamination
typically found in graywater have impeded the practice from gaining wide-scale application in the United States.
Simple treatment schemes, such as those using constructed wetlands, could reduce graywater pollution and allow for
more reuse applications.
This report documents the results of a study examining the treatment potential of constructed wetlands on graywater.
The specific objectives of this research were to demonstrate the treatment efficiency of wetlands on graywater,
determine whether wetland treatment produced water suitable for reuse, and assess the primary contact risks of the
graywater in the wetland and treated effluent. A constructed graywater wetland scheme featuring a free water surface
(FWS) bed followed in series by a subsurface flow (SF) bed was built and investigated on the campus of Colorado
State University (CSU). Built at the pilot-scale, the wetland was evaluated using graywater, i.e., hand wash and
shower water only, over a one year period. Water quality samples were taken from three locations in the wetland
system: influent, effluent of the FWS, and effluent from the SF. Samples were collected and analyzed approximately
every three weeks following the procedure given in the quality assurance project plan (QAPP) approved by the EPA
prior to sampling. Samples were analyzed for a wide range of water quality parameters including organics, solids,
nutrients, indicator microorganisms, and surfactants. Additionally, detailed assessments of flow and hydraulic
retention times (HRT) were conducted to evaluate the hydraulics of the wetland. The wide range of measurements
taken provides a comprehensive assessment of the treatment of graywater via wetland systems.
Results of water quality measurements showed that the wetland substantially reduced organics, solids, nutrients,
pathogens, and surfactants throughout the sampling period. A majority of the removal for all constituents was found
to occur in the FWS; however, the effluent quality of the FWS suffered from considerable algae growth in the open
water which maintained elevated levels of TSS and turbidity. Further conditioning in the SF removed most of these
solids. Flow monitoring through the wetland indicated significant flow losses during warm months resulting from
evapotranspiration losses, which decreased the amount of effluent available for reuse. Throughout the experiment, no
odor issues were noticed and no detrimental effects on plant growth from using graywater were observed.
By way of this research, constructed wetlands were shown to be a viable means to condition graywater for reuse. In
particular, removal rates of biochemical oxygen demand and total suspended solids averaged 91% and 77%
respectively, while removal of anionic surfactants averaged 94% and did not drop below seasonal mean of 88%
throughout the year. The wetland reduced pathogenic indicator microorganism concentrations by approximately two
orders of magnitude on average, producing effluent concentrations below primary contact standards for all seasons
except winter. A comparison of the wetland effluent quality with Colorado state reclaimed water quality regulations
showed that effluent would typically meet reclaimed water quality standards for restricted irrigation reuse although
effluent would not meet standards of same states that had stricter microbial regulations. In addition, given the limited
assessment performed during this study, as compared to EPA regulations governing recreational swimming waters,
the graywater wetland effluent contained adequately low number of select bacteria but was not considered to have an
average of non-detect as required; as such greywater would potentially exceed national recreational contract
standards.
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In particular, winter removal efficiencies were lowest of any season, producing effluent with Escherichia coll,
biochemical oxygen demand, and turbidity levels above EPA recommended reclaimed water standards. The wetland
effluent would not meet unrestricted irrigation standards consistently throughout the year. If unrestricted landscape
irrigation is desired, the wetland effluent would require additional treatment including disinfection prior to reuse
during the winter. However, if the wetland's effluent is intended for irrigation purposes, typically irrigation would not
be carried out during the winter season and the potential for primary contact would be minimized.
Whether or not the above reclaimed water regulations truly represent the acceptable risk to humans and the
environment from graywater reuse remains a matter of further investigation. Additional microbial analyses could
better reveal the true pathogenic risks. It is believed that the scale and duration of this evaluation, along with the wide
range of measurements taken, could promote additional research and application of wetland treatment of graywater.
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Chapter 1 Introduction
This report documents the results of a study examining the efficiency of a pilot-scale constructed wetland system for
treating graywater over a one year period, and explores the potential for onsite reuse of the treated effluent for outdoor
irrigation. The wide range of measurements taken, including those of anionic surfactants and pathogenic indicator
microorganisms, provides a comprehensive assessment of the treatment efficiency and outflow water quality
characteristics of such systems.
Overview
Mounting pressure to conserve water resources has prompted the notion that the separation of graywater (all
wastewater not including toilet and kitchen sources) from sewer effluents through the use of dual-plumbed systems
may enable it to be reused at the household level for such non-potable demands as landscape irrigation or toilet
flushing. Estimates of graywater generation rates vary, with several studies reporting as much as 50-80% of
residential wastewater being graywater (Gross et al., 2007a). Past studies have shown significant reductions in water
demands, wastewater generation rates, and associated costs resulting from graywater reuse. Such potential water and
cost savings have prompted several European and Asian countries to adapt graywater reuse on a wide scale basis.
However, in the United States (U.S.), water quality and health concerns arising from the level of contamination
typically found in graywater have impeded graywater reuse from gaining wide-scale application. In particular, levels
of solids and organics (e.g. Eriksson et al., 2002) as well as pathogens (Rose et al., 1991) in graywater have been
shown to regularly exceed reuse and primary contact regulations.
Simple treatment schemes, such as those using constructed wetlands, could reduce graywater pollution and allow for
more reuse applications. The efficacy and the design of wetlands for municipal wastewater streams have been
documented by EPA (EPA 2000a and 2000b). Wetland systems can take on various designs, with two of the most
common being the free water surface (FWS) and subsurface flow (SF) types. FWS wetlands feature open water
similar to natural wetlands, while SF wetlands contain a matrix of sand or gravel through which water flow and in
which vegetation is rooted (EPA, 2000a). The use of constructed wetlands for treating graywater has had few
applications (and none in the U.S.). Past studies involving treatment of graywater using various wetland
configurations have shown promising pollution removal efficiencies (Dallas and Ho, 2005; Winward et al, 2008b;
Gross et al., 2007b); however, these wetland treatment systems were small, highly controlled, and operated over short
periods of time. Specifically, the study by Winward et al. (2008a) featured horizontal wetlands supplied with low-load
graywater. These wetlands were quite small and operated in a greenhouse, but with only a 2.1 day hydraulic retention
time (HRT) achieved mean biochemical oxygen demand (BOD5) and total suspended solids (TSS) removal rates of
90% and 63% respectively. Other published graywater wetland treatment schemes have been designed on a similarly
small scale as above, and information is lacking on the long term performance of such systems at the pilot scale. In
particular, no studies have examined the treatment effects of combining FWS and SF systems.
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This report details a novel constructed graywater wetland treatment scheme involving both a FWS and SF in tandem
to treat graywater from a building. Built at the pilot-scale, the wetland was evaluated using low-load graywater from a
Colorado State University (CSU) building with a design graywater flow of 330 L/d. Water quality samples were taken
from three locations in the wetland approximately every three weeks and were analyzed for temperature, pH,
turbidity, dissolved oxygen (DO), specific conductivity (SC), total organic carbon (TOC), BOD5, total nitrogen (TN),
dissolved total nitrogen (DTN), ammonia (NH3), nitrate (NO3~), total phosphorus (TP), phosphate (PO43~), chloride
(Cl~), sulfate (SO42~), Escherichia coll (E. coli), TSS, total dissolved solids (TDS), total volatile solids (TVS), volatile
suspended solids (VSS), and anionic surfactants. Additionally, detailed assessments of flow and HRT were conducted
to evaluate the hydraulics of the wetland. The above water quality parameters were chosen as they represent a detailed
assessment of the overall effluent water quality, specifically for irrigation reuse applications. In its current
configuration, due to local regulations, the graywater wetland effluent is not reused; however, there is potential to use
the effluent in the future for landscape irrigation on the grounds of CSU. The treatment system here could also be
modified or added to if other end uses of the graywater, e.g. toilet flushing, were desired.
Objectives
The objectives of this research were to demonstrate the treatment potential of wetlands on graywater, determine
whether wetland treatment produced water suitable for reuse, particularly as irrigation water, and assess the primary
contact risks of the graywater in the wetland and of the treated effluent.
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Chapter 2 Conclusions and Recommendations
Wetland Performance
Results of water quality measurements showed that the wetland substantially reduced organics, solids, nutrients,
pathogens, and surfactants throughout the sampling period. In particular, removal rates of BOD5 and TSS averaged
91% and 77%, respectively, while removal of anionic surfactants averaged approximately 88% or more throughout
the year. Removal rates of nutrients, i.e., TN and TP, were 84% and 77%, respectively.
The majority of the removal for all constituents was found to occur in the FWS, however, the effluent quality of the
FWS suffered from considerable algae growth in the open water of this system. These algae contributed elevated
levels of TSS and turbidity. Further treatment in the SF removed most of these solids in the spring months. Through
the summer months TSS and turbidity levels were lower in the FWS effluent but these increased in the SF effluent,
likely a result of biofilm formation on gravel matrix in the SF. Increased vegetation density in the FWS during the
first summer may have reduced the high algae growth, due to shading of open water. Future spring seasons may not
have as high TSS effluent conditions, as this was the first season monitored and the system was still being established.
This research demonstrated that constructed wetlands may be a viable means to condition graywater for reuse. A
comparison of the wetland effluent quality with state reclaimed water quality regulations showed that effluent would
typically meet reclaimed water quality standards for restricted irrigation reuse. Also, in comparison to EPA
regulations governing primary contact, i.e., recreational swimming waters, the graywater wetland effluent contained
sufficiently low values of select bacteria for all seasons except winter. The wetland's treated effluent was intended for
irrigation purposes, which would not be carried out during the winter, reducing the potential for primary contact.
Unfortunately, during the summer months when irrigation water would be most beneficial, little effluent was
observed beyond the FWS cell. In this particular study, this is attributed to the following three factors, the first two of
which are attributable to the arid climate: high evapotranspiration rates, limited direct rainfall and decreased
production of graywater.
The wetland effluent did not meet unrestricted standards consistently throughout the year. In particular, winter
removal efficiencies were lowest of any season, producing effluent with E. coll, BOD5, and turbidity levels above
both EPA recommended reclaimed water guidelines and primary contact regulations. If unrestricted urban landscape
irrigation is desired, the effluent would require additional treatment including disinfection prior to reuse in winter
months. If the effluent were to be collected indoor use, i.e. toilet flushing, additional treatment including disinfection
would also be necessary. Whether or not the current reclaimed water guidelines truly represent the acceptable risk to
humans and the environment from graywater reuse remains a matter of further investigation. The main pathway to
infection from any wastewater remains "fecal-oral" transmission (EPA, 2004) though skin contact and inhalation are
other vectors for disease transmission. As graywater systems separate out black water, the primary source of fecal
material is not present in this treated wastewater. Reducing risk of disease transmission by graywater systems may be
as simples as prohibiting spray irrigation system by using drip systems only, as aerosols from spray irrigation may
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contain pathogens (viruses and bacteria - EPA, 2004), requiring safety procedure for those handling systems, i.e.,
wearing gloves and washing hands after coming in contact with the gray water system components, or incorporating
disinfection treatment, as necessary. Many such safety procedures have been incorporated into a Water Environment
Research Foundation (WERF) Final Report (Bergdolt et al., 2011) entitled "Guidance Manual of Graywater from
Blackwater for Graywater Reuse.
Further microbial analyses could potentially belter reveal the true pathogenic risks. It is believed that the scale and
duration of this evaluation, along with the wide range of measurements taken, could promote further research and/or
application of wetland treatment of graywater.
Public Acceptance
It is surmised that public acceptance of wetland treatment of graywater hinges primarily on public safety and
aesthetics. Public safety risks, primarily through contact with graywater, are inherent unless access to wetland water is
restricted. As in the case of SF wetlands, public access is easily restricted without any perimeter barriers which could
be considered more appealing in urban areas. Aesthetically, wetland treatment is considered highly pleasing as a BMP
for WWF, and wetland treatment of graywater should be no different. Throughout the experiment, no odor issues
were noticed and no detrimental effects on plant growth from using graywater were observed. In fact, both the cattail
and bulrush appeared to grow more quickly after irrigated with graywater shortly after vegetation establishment. Only
after winter ice melted was the FWS considered mildly unattractive when algal growth in the FWS was prolific and
formed thick bloom mats. However, algal blooms lasted only a week, quickly dissipating with warming temperatures.
Several animal and bird species frequented the wetland, which added to the overall aesthetic appeal. Such multiple
benefits, i.e., water treatment, animal habitat, and green space, should increase the public acceptance of graywater
wetlands. Additionally, such treatment is typically seen as more sustainable than traditional wastewater management
methods, which may also increase public approval. As with any open treatment system, it should be noted that
animals and birds are potentially additional vectors for nutrient and pathogenic indicators.
Recommendations for Future Study
Data in this report represents one year of data collection from the pilot-constructed wetland facility. Long-term
monitoring past the one year mark would further demonstrate the wetland treatment potential, especially since the
sampling results presented were within the first year of wetland establishment. Other future research should include:
1. Further seasonal data collection to verify effects observed in this study.
2. Studying graywater wetlands in other climatic conditions.
3. Further monitoring of the salinity content of the effluent (as it was shown to increase through the wetland and
salinity content is a concern for landscape irrigation waters).
4. Investigating the metals and trace contaminant content (particularly pharmaceuticals and personal care
products) of the wetlands' plants, soils, and treated effluent.
5. Determining the optimal loading rates of the wetland to achieve specific end purposes, i.e., potentially
decreasing winter hydraulic loading rates to meet unrestricted contact for irrigation waters and increasing
summer hydraulic loadings to produce sufficient effluent for irrigation.
6. Examining in detail the economics and public acceptance of using wetlands for graywater treatment as
opposed to other treatment mechanisms.
7. Addressing the legal issues of reusing the wetland effluent both on local and state levels.
8. Investigating supplementary disinfection and/or secondary treatment, particularly during winter months or if
the wetland effluent must be held to reclaimed water standards.
9. Investigating the full suite of pathogen indicator organisms and tracking specific viral pathogens to have a
greater sense of the true risk of the discharge from graywater treatment systems.
10. If the purpose is to develop a source of unrestricted irrigation water for summer use, in arid areas, design
modifications to the current system might be needed. This could entail adjusting sizing or flow through of the
wetland system or seasonally adjusting sources of graywater need sources.
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Chapter 3 Background
Graywater Definition, Quantity, and Reuse Savings
A general definition of graywater (also spelled greywater) is all wastewater not including contributions from toilets;
however, in the U.S., this definition also excludes kitchen sources. Further restrictions on the definition of graywater
can be made by more closely specifying the source of graywater; for example, Friedler (2004) and Winward et al.
(2008a) define low-load graywater as coming from showers, baths, and sink faucet while excluding kitchen and
laundry sources.
Estimates of graywater generation rates vary, with several studies reporting as much as 50-80% of residential
wastewater being graywater (Gross et al., 2007a). An American Water Works Association sponsored study of 1,200
households across 14 North American cities found that on average over 50% of all residential indoor water demands
generate graywater (Mayer et al., 1999). This same study showed that on average over 50% of all residential potable
water is used for outdoor irrigation, the largest single residential demand. Considering this large demand and that the
source for outdoor irrigation water need not be of the same quality as indoor potable water, reusing graywater for
irrigation offers a substantial water savings. In addition to landscape irrigation, recycled graywater is a potential
source for other demands not requiring potable source water, such as toilet flushing.
The degree to which graywater reuse can reduce household potable water demand is variable depending on
geographical location, landscaping preferences, and personal water use habits. Karpiscak et al. (2001) and the City of
Los Angeles (1992) among others have estimated that reusing graywater for outdoor irrigation and toilet flushing
could reduce household water demand by 20-50%. In addition to reducing total water demand, recycling graywater
reduces total wastewater generation rates, and is viewed as a much more efficient reuse alternative as compared with,
for example, reusing wastewater effluent. This is because graywater is produced and used directly at the residence and
requires very little infrastructure modifications or delivery costs.
Graywater Quality
Such potential water and cost savings have prompted several European and Asian countries to adapt graywater reuse
on a wide-scale basis, and have provoked increasing interest in the practice in the U.S. However, many U.S. states do
not advocate the practice due to environmental and public health concerns arising from the potential chemical and
microbial content of graywater.
Physical and Chemical Properties of Graywater
The physical and chemical properties of graywater are highly variable depending on the source, and are influenced by
many factors including the number of household occupants, types of cleaners and personal care products used,
grooming and hygiene habits, and sink waste disposal practices (Eriksson et al., 2002). Concentration ranges for
common water quality constituents compiled from three studies are listed in Table 3-1. The values presented for
Eriksson et al. (2002) are for low-load graywater only derived from bathroom sinks, showers, and baths. The values
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from Rose et al. (1991) are in reference to graywater not including kitchen sources composited in a storage tank. The
values from Gross et al. (2007b) refer to graywater mixed artificially to replicate graywater from mixed sources.
Table 3-1. Graywater Quality Characteristics from Literature
Pollutant
(mg/L)1
pH
EC, uS cm'1
BOD5
TOC
TN
NH3
NO3-
TP
po43-
so42-
cr
TSS
TDS
Turbidity, NTU
Anionic Surfactants
Source of Graywater
Bathroom2
6.4-8.1
82 - 250
76 - 200
30 - 104
5-17
<0.1-15
0.3-6.3
0.1-2
0.9-49
_
9-18
54 - 200
137 - 1260
28 - 240
Composite3
6.54
_
_
_
1.7
0.74
0.98
_
9.3
22.9
9.0
_
76.3
Composite4
6.3-7.0
1,000 - 1,300
280 - 688
_
25-45
0.1-0.5
0-5.8
17.2-27
_
_
_
85 - 285
_
4.7-15.6
All units in mg/L unless otherwise noted.
2 Eriksson et al. (2002); values of TP and PO43" taken from different studies of bathroom water.
3Roseetal. (1991).
4 Gross et al. (2007b).
Microbial Properties of Graywater
The quantities of microbial indicators in graywater are highly variable, but generally have been shown to regularly
exceed state water reuse or primary contact regulations (Rose et al., 1991; Cassanova et al., 2001). Commonly
measured bacteria for indicating fecal contamination include total coliforms, fecal coliforms, E. coll, and enterococci.
Of these, fecal coliforms and E. coll are the principle indicators of pathogenic enteric bacteria, while enterococci are
often used to indicate fecal virus contamination. Traditionally, fecal coliform levels are used to determine the degree
of fecal contamination; however, many states, including Colorado, have recently moved to adopt E. coll levels as the
primary indicator (CDPHE, 2007). E. coll are thought to be entirely of fecal origin, as opposed to coliform bacteria
which are known to grow in soil (Tchobanoglous and Burton, 1991), and therefore the substrate of the graywater
system.
Concentrations of fecal indicators in stored graywater can be higher than freshly generated graywater, indicating that
microbial growth occurs in storage tanks (Dixon et al., 1999). Rose et al. (1991) indicated that shower and bath
wastewater are likely vectors of fecal contamination. A comparison of microbial levels in graywater of various
sources from several studies is presented in Table 3-2.
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Table 3-2. Microbial Quality of Graywater
Graywater
Sources
Composite
Composite
Composite
Bath & shower
Bath & shower1
Composite
Fecal coliforms
(cells/100 mL)
5.6 x 105
1.8xl04-7.9xl06
-
10° -3.3xl03
6xl02
-
E. coli
(cells/100 mL)
-
-
10° -2.4xl08
<102-2.8xl03
-
<102 -6.3xl03
Enterococci
(cells/100 mL)
-
-
101 -2.7xl05
-
-
<102 -5.0xl03
Reference
Casanova et al. (2001)
Roseetal. (1991)1
Eriksson et al. (2002)
Eriksson et al. (2002)
Surendran et al. (1998)
Winward et al. (2008b)
From university residence halls
Surfactants
In addition to the aforementioned graywater quality constituents, recent interest has been paid to the effects of
personal care products on the soils and plants receiving graywater irrigation. Surfactants represent one common class
of graywater contamination arising from personal care products. These chemicals are found in most soaps and
detergents, and are used to lower the surface tension of a liquid such to allow emulsification of hydrophobic
compounds. Surfactants are classified by their ionic state: nonionic, cationic, anionic, and amphoteric. Many of the
surfactants in common soaps and body cleansers fall in the anionic category, and include: sodium dodecyl sulfate,
ammonium lauryl sulfate, linear alkyl benzene sulfonate (LAS).
While many of the above anionic surfactants are not directly toxic through contact or consumption, they may pose
threats to human health via environmental accumulation or through the toxicity and xenobiotic characteristics of their
degradation byproducts (Shcherbakova, 1999). Anionic surfactants have been shown to exist in graywater at elevated
levels, with Gross et al. (2007b) reporting concentrations in the range of 4.7 - 15.6 mg/L.
Applicable Water Quality Standards
Although few water quality regulations exist specifically for onsite graywater reuse, urban water reuse standards -
developed primarily for reclaimed wastewater effluent - provide a useful comparison by which to evaluate graywater
quality. Several states have developed reuse regulations and/or guidelines specific to the end use of the reused water
(Table 3-3). The EPA (2004) gives the following suggested guidelines for reclaimed water for such types of reuse as
urban (e.g., all landscape irrigation, vehicle washing, toilet flushing, and other uses with unrestricted exposure) and
recreational impoundments, i.e., for incidental and full body contact: pH = 6-9, BOD5 < 10 mg/L, turbidity < 2 NTU,
and no detectable fecal coliforms per 100 mL of sample. EPA reuse guidelines given for other applications are less
stringent, such as those for restricted or agricultural irrigation, industrial reuse, and landscape impoundments: pH = 6-
9, BOD5 < 30 mg/L, TSS < 30 mg/L, and fecal coliforms < 200 MPN/100 mL. However, there are stricter guidelines
for indirect potable reuse and food crops not subject to commercial processing.
-------
Table 3-3. State Reclaimed Water Quality Standards for Unrestricted Urban Reuse (EPA, 2004)
State
Treatment
Pollutant
BOD5 (mg/L)
TSS (mg/L)
Turbidity
(NTU)
lotai
Coliform
Fecal
Coliform
Arizona
Secondary
treatment,
filtration,
&
disinfection
California
Oxidized,
coagulated,
filtered, and
disinfected
Florida
Secondary
treatment,
filtration,
and high-
level
disinfection
Hawaii
Oxidized,
filtered, and
disinfected
Nevada
Secondary
treatment
and
disinfection
Texas
Not
Specified
Washington
Oxidized,
coagulated,
filtered, and
disinfected
Water Quality Standard
NS
NS
2 (mean)
5 (max)
NS
Non-detect
(mean)
23/100 mL
(max)
NS
NS
2 (mean)
5 (max)
2.2/100 mL
(mean)
23/100 mL
(max in 30
days)
20 mg/L
5.0 mg/L
NS
NS
75% of
samples
below
detection
25/100 mL
(max)
NS
NS
2 (max)
NS
2.2/100 mL
(mean)
23/100 mL
(max)
30 mg/L
NS
NS
NS
2.2/100 mL
(mean)
23/100 mL
(max)
5 mg/L1
NS
o
3
NS
20/100 mL
(mean)
75/100 mL
(max)
30 mg/L
30 mg/L
2 (mean)
5 (max)
NS
2.2/100 mL
(mean)
23/100 mL
(max)
This increases to 10 mg/L for landscape impoundments.
2 NS - No Standard.
EPA primary contact regulations for fecal coliforms and E. coll are provided in Table 3-4. Reuse regulations specific
to Colorado are based primarily on turbidity and E. coll numbers (CDPHE, 2008). Colorado specifies that E. coll
concentrations be undetectable in over 75% of sample for unrestricted landscape irrigation and meet primary contact
regulations (Table 3-4) for restricted reuse. The regulations limit turbidity to less than 3 NTU on a monthly average
for unrestricted irrigation. No turbidity standards are given for restricted reuse; instead a TSS limit of 30 mg/L is
applied.
Table 3-4. Pathogen Indicator Limits for Primary Contact in Freshwater (EPA, 1986)
Pathogen
Indicator
Enterococci
E. coli
Fecal Coliform2
30-day Geometric
Mean, cells/100 mL
200
126
33
Single Sample Maximum
75th percentile, cells/100 mL1
375
235
62
For infrequent bathing.
2 Extrapolated values based on equations presented in EPA (1986).
Aerosols from spray irrigation may contain viruses and bacteria which can come into contact with humans (EPA,
2004 and Bergdolt et al., 2011). The strict microbial standards presented in Table 3-4 for landscape irrigation would
necessitate disinfection of recycled graywater, however if non-contact subsurface (drip) irrigation is performed,
potential human contact would eliminated and these microbial standards could be viewed as overly cautious. Previous
studies have suggested microbial regulations developed for primary contact recreational waters are applicable to
recycled graywater since activities associated with primary contact recreational water and with graywater reuse both
involve body exposure and accidental ingestion (Dixon et al., 1999).
10
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Salinity, typically measured as SC, guidelines are not included in the above reuse guidelines. However, salinity is an
important parameter to consider when using recycled water for irrigation since high salinity can reduce osmotic
potential in plant cells, subsequently causing plant mortality. The Florida Cooperative Extension Service (FCES,
2004) recommended SC levels for irrigation water below 750 uS/cm.
Constructed Wetlands
Elevated pathogen indicator numbers in graywater make treatment desirable, if not necessary, for graywater reuse to
gain wide-scale public acceptance and application. Many treatment systems have been proposed to condition
graywater. For instance, Friedler et al. (2006) evaluated three technologies commonly used in municipal wastewater
treatment on graywater: sand-bed filtration, membrane bioreactors (MBR), and biological contactors. These
mechanical/biological treatment units showed effective graywater treatment; however, their application at a
household level would require considerable time and large expenditures. Sand filtration units for instance require
frequent back flushing, and MBRs have extensive operation and maintenance requirements. An alternative to
mechanical treatment of graywater may be the use of constructed wetlands.
Constructed wetlands are treatment systems that replicate natural wetlands to improve water quality through physical,
chemical, and biological treatment mechanisms (Kadlec and Knight, 1996), and are commonly employed to treat
municipal wastewater (Tchobanoglous et al., 2003; EPA 2000a; and, Hammer, 1989). Not only can constructed
wetlands provide important water quality improvements with low energy and maintenance requirements, wetlands can
also offer pleasing aesthetics, ecological benefits, and wildlife habitat (EPA, 2000a).
Common Constructed Wetland Designs
Constructed wetlands can have a variety of designs, with two of the most common being the free water surface (FWS)
and the subsurface flow (SF) types (Figure 3-1). FWS closely resemble natural wetlands in both appearance and
function, and feature elements typical of a natural wetland such as emergent vegetation and open-water areas (EPA,
2000a). SF wetlands contain a bed of gravel or sand in which aquatic plants are rooted. Water passes through the
matrix and root zone, but is not exposed to the surface; therefore water is not visible or accessible by humans or
wildlife. Because of the large surface contact of the growth matrix, SF wetlands feature higher microbial reaction
rates for most contaminants than FWS wetlands, which reduce the required footprints of SF wetland (EPA, 2000c).
However, if loaded with high-solid content influent or if too fine a matrix is employed, SF wetlands may clog.
Figure 3-1. Typical free water surface (left) and subsurface flow (right) wetland configurations.
Wetland Treatment Mechanisms
Wetlands reduce pollutants via sedimentation, biodegradation, filtration, plant uptake and storage, and volatilization
(EPA, 2000a). The primary variables influencing the degree to which the above wetland mechanisms treat process
water are HRT and water temperature (Kadlec and Knight, 1996; Hammer, 1989). Increasing HRT results in a longer
contact time and more efficient contaminant treatment, while lower water temperatures reduce reaction kinetics and
subsequently treatment rates. Hence, it is generally expected that treatment efficiency is the lowest during winter
months when temperatures are the coldest.
Microbial treatment in wetlands results primarily by settling, predation, solar irradiation, and temperature inactivation
(Kadlec and Knight, 1996). Close correlations of TSS removal with pathogen (and indicator) removal have been
reported (EPA, 2000a), with HRT being the primary factor influencing pathogen treatment efficiency. While
11
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treatment rates of fecal pathogenic indicators in constructed wetlands vary widely by design, operation, and location,
observed reductions of one to three orders of magnitude are common in wetlands treating municipal sewage.
Wetland Hydrology
Because the HRT of a wetland system is the preeminent criteria to determine treatment efficiency, a sound
understanding of wetland hydrology is necessary for adequate design and operation of such systems. Wetland
hydrology characterizes the pattern of the inflows and outflows through the wetland system. Inflows can include
direct influent inputs, precipitation, runoff intrusions, and groundwater contributions. Outflows include effluent flows,
evapotranspiration (ET), and losses to groundwater. In natural wetland systems, the balance of these inflows and
outflows continually adjust the storage volume in the wetland. Constructed wetlands, however, are typically designed
to maintain a fixed water depth and volume and to limit groundwater fluxes and runoff inflows. In this way, the HRT
can be managed to achieve the desired level of treatment.
HRT is defined as the ratio of total void volume (or water volume) to inflow rate. Void volume is the part of the total
volume available through which water may flow, and is simply the total wetland volume less any volume occupied by
plants, water regulation structures, matrix (substrate) and piping. Void volume may be computed by multiplying the
total volume by the porosity of the wetland. Wetland porosity varies by matrix, vegetation, and age, with more
established wetlands having a lower porosity than recently established wetlands. FWS wetlands generally have
greater porosities than SF wetlands due to the sand or gravel matrix in SF types. The EPA (2000a) reports FWS
porosities between 0.65 and 0.95, with a value of 0.75 given for medium dense, fully established wetlands. Porosity
values for SF wetlands mainly depend on the mean size of the gravel or sand growth matrix. Typical SF matrix
porosity values range from 0.26 for course sand to 0.45 for course rock (EPA, 2000c).
12
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Chapter 4 Materials and Methods
A pilot-scale constructed wetland system was built during the summer of 2007 at CSU. The system was built to
receive and treat graywater from a campus building comprised of office and laboratory space. Upon completion of
construction, the wetland was vegetated with wetland vegetation typical of the region. Supplemental graywater was
provided from a residential dormitory and after reaching hydraulic equilibrium, a one-year study of the treatment
effectiveness and effluent quality of the wetland was initiated to determine the suitability of the wetland effluent for
reuse purposes. This chapter provides a description of the graywater wetland system, and describes the methods and
materials used to monitor the physical, chemical, and microbial characteristics of the system.
Wetland Configuration
The graywater wetland was constructed at the base of a steep grade below the Atmospheric Chemistry Building
(ACB) on the CSU Foothills Campus (Figure 4-1). Because of state and local permitting requirements, effluent from
the graywater wetland was also routed back to the municipal sewer after passing through the wetland system.
In its current configuration, effluent from the wetland was not reused due to state regulations; however, there is future
potential to use the effluent for landscape irrigation on the grounds of CSU. CSU currently uses non-potabale water
for irrigation, and could supplement their irrigation water with the wetland effluent either directly or indirectly. If
done directly, the effluent would be released to the surface where it would likely flow to the Colorado State Forest
Service grounds (Figure 4-1) where it could be used for tree irrigation.
The graywater wetland consisted of two beds in series: a FWS bed followed by a SF bed (Figure 4-2). This
arrangement was designed to promote settling of course materials in the FWS before reaching the SF, preventing
clogging of the SF gravel matrix. Each wetland bed was constructed with distribution and collection headers to
facilitate flow dispersion, denoted "e" in Figure 4-2, impermeable bottom liners to prevent groundwater flux, denoted
"b", and perimeter berms to prevent runoff intrusion and rip-rapped side slopes, denoted "c". Overflow inlets, "f',
were provided in the event of the header blockage. Manholes were constructed at each inflow and outflow location,
and contained piping to regulate water depth in the beds and flow meters, denoted "g". Manholes were denoted
numerically, with Manhole # 1 being upstream of the wetland system, Manhole #2 located downstream of the FWS
wetland and Manhole #3 located downstream of the SW wetland (Figure 4-2). The respective substrate for each
wetland is denoted "d" and "h", while "a" is a compositing tank.
A 300 L high density polyethylene (HDPE) storage tank, located upstream of the FWS and denoted by "a" in Figure
4-2, composited the inflow for sampling. The tank was sized to collect approximately a one day composite sample.
Due to footprint and plumbing limitations, the final volume of the composite tank was 300 L.
13
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/
Sewer Connection
Man hole #3
Existing
Sewer
Line
i
3" Line from Building
SCAU: 1*« 20*
Figure 4-1. Graywaterwetland location and layout. (Aerial photo© DigitalGlobe, 2009)
F WS Wetland
Manhole »2
Key
a. Composite tank e. Headers
b. Impermeable liner f. Overflow inlets
c. Rip rap g. Flow meters
d. Substrate FWS h. Substrate SF
Figure 4-2. Graywater wetland configuration.
The size of the wetland was based on expected flow and pollutant loading rates. Graywater inflow rate was estimated
assuming a building occupancy of 38 people and an average graywater generation rate of 5.7 L/cap/d giving a design
graywater flow rate of 216 L/d. The design for the wetland anticipated removing over 99% of BOD5 and TSS, even
during winter months. Based on these criteria, an estimated flow (void) volume of 4.6 m3 was specified resulting in a
HRT of approximately 21 days.
14
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Free Water Surface Design and Operation
The FWS bed measured 2.7 m by 3.7 m and maintained a water depth of approximately 0.3 m (Figure 4-3 and Figure
4-4). It was given a 2:1 (rise-to-run), rip-rapped side slope, and was planted with common cattails (Typha latifolia).
The base of the FWS bed was filled with 0.9 m of amended soil, denoted letter "d" in Figure 4-2, consisting of
approximately 50% native soil and 50% peat. The FWS volume was approximated at 2010 L assuming an overall
vegetation porosity (TJ) of 0.8. The EPA (2000a) reports a porosity value of 0.75 for medium dense, fully established
wetlands. Because it was uncertain how quickly the wetlands in this location would become fully established and
porosity was important in computing effluent volumes and hydraulic retention times, the porosity of the FWS bed was
computed by estimating that 80% of the bed was covered in medium-dense, established vegetation with a mean
porosity of 0.75 (EPA, 2000a) and 20% of the FWS was open water (TJ = 1.0), leading to an overall weighted porosity
of 0.8. The HRT of the FWS was nominally 9.3 d based on 216 L/d.
a
Figure 4-3. Freshwater surface wetland spring 2009.
Figure 4-4. Freshwater surface wetland fall 2009.
The cattails in the FWS bed were established in September 2007 at a density of one plant per 0.3 m2. The cattails were
irrigated with municipal water for the first 45 days after planting and afterwards with graywater. Cattails grew
vigorously the first two months of establishment, growing approximately 0.35 m in the first 43 days after planting.
After winter dormancy, the cattails resumed active growth in May, 2008, reaching a final mean height of 1.4 m by the
fall of 2008. Plant heights were determined by measuring and averaging the height of 12 plants selected at random.
The cattails also spread via rhizome migration to cover nearly 80% of the bottom of the FWS bed by fall 2008. By
August 2009 the cattails were approximately 2 m tall and covered well over 80% of the bottom of the FWS bed.
15
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Subsurface Flow Wetland Design and Operation
The SF bed was nominally 3.7 m by 4.6 m, and given a water depth of 0.6 m this provided a volume of 10.2 m3. The
SF was built with 2:1 rip-rapped side slopes (Figure 4-5 and Figure 4-6 and denoted by "h" in Figure 4-2). The SF
was filled with cleaned, rounded native stone with an approximate mean diameter of 15 mm, and planted with
hardstem bulrushes (Scirpus acutus). Porosity was physically measured by excavating the gravel and root matrix and
placing in a bucket. The gravel and root matrix was allowed to drain and dry. Porosity was estimated by filling the
bucket with a measured amount of water and then dividing by the total bucket volume (11.4 L). The procedure was
completed for three locations in the wetland selected at random (Table 4-1). SF void volume was approximately 2610
L considering an average porosity of 0.29 for the gravel and established root matrix. The HRT of the SF was
nominally 12.1 d based on 216 L/d.
...
Figure 4-5. Subsurface wetland spring 2009.
Figure 4-6. Subsurface wetland fall 2009.
Table 4-1. Porosity Determination of the Subsurface Flow Wetland
Locations
1
2
3
Total
Volume (L)
11.4
11.4
11.4
Mean
Void
Volume (L)
4.3
2.5
3.0
3.3
Porosity
0.38
0.22
0.26
0.29
16
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Bulrushes in the SF bed were first established in September 2007 at a density of one plant per 0.3 m2. Because they
were planted late in the growing season and experienced an unusually cold winter in 2007/2008, the bulrushes
suffered 100% mortality and were replanted in May, 2008. The bulrushes were watered with tap water for
approximately 120 days after planting in 2008. The great length of time during which the SF was watered with tap
water was due to a lack of graywater from the ACB as described under the heading "Graywater Sources". After
supplemental graywater was acquired from a CSU dormitory, the bulrushes were switched to graywater irrigation.
Because they were rooted in cleaned gravel void of any nutrients and irrigated with tap water, supplemental nutrients
were supplied to the bulrush for approximately 90 days following planting in May, 2008. Soluble garden fertilizer
was provided at a rate of 0.25 kg/wk in the following ratio: 24% N; 8% P; and 16% K. After this establishment
period, nutrient application ceased 30 days prior to the introduction of graywater to allow the system to equilibrate.
Very little mortality was observed over the winter of 2008/2009, and by spring 2009, the bulrushes had spread to
occupy approximately 50% of the SF area.
Graywater Sources
Low-load graywater was provided to the wetland primarily from two sources: lavatory sink water from the dual-
plumbed ACB, and lavatory sink and shower water from a residential dormitory.
Atmospheric Chemistry Building Graywater
The ACB was built with separate wastewater plumbing to separate blackwater (i.e., toilet water), lab water and
graywater from lavatory sinks. Blackwater and lab water were routed directly to the municipal sewer, while ACB
graywater was collected from sinks in four lavatories, which were plumbed directly to the wetland. Initial flow
measurements during summer, 2008 showed an average graywater flow rate of 59 L/d being produced in the ACB, far
less than the peak 216 L/d that was anticipated. Graywater flow rates were lower than expected because the building
was not fully occupied. The estimated occupancy throughout the experiment was 20 persons as compared to the
expected 38. Graywater production in the ACB occurred almost entirely during weekdays, with nearly no flow
observed during weekends. Such low flow rates were less than the daily seepage and ET rates observed in the FWS,
which prohibited any flow from reaching the SF wetland and necessitated that supplemental graywater be provided.
Dormitory Graywater and Transfer System
Supplemental graywater was provided from a residential dormitory at CSU. Dormitory graywater was collected from
sinks from three communal lavatories serving approximately 72 residents and from showers serving approximately 24
residents. Graywater was collected in the basement of the dormitory in a 1,100 L HDPE tank (Figure 4-7), where it
was stored until transfer. Transfer and hauling to the wetland site was conducted every three days via a 1,800 L
stainless steel, trailer-mounted tank (Figure 4-8). At the wetland site, the hauled graywater was dispensed using a
variable speed, peristaltic metering pump (Masterflex VA10, Vernon Hills, Illinois) into Manhole #1 where it was
mixed with the ACB graywater before gravity flowing to the wetland system. Dormitory graywater was hauled to the
wetland twice a week during the experiment, restricting the average residence time of the water in the trailer-mounted
tank to under approximately 3.5 days.
The metering pump was housed in an insulated pump box (Figure 4-9). In the pump box, approximately 3.5 m of 6.5
mm diameter tubing was coiled around a 75 W heat source (light bulb) to prevent freezing during transfer between the
pump box and the manhole in the winter. The pump box heat source was wired through a household thermostat (set at
27 °C) to prevent overheating and conserve electricity. Other freeze prevention measures included insulating all
exposed piping between the tank and manhole and installing a 500 W submersible heater in the trailer-mounted tank.
The submersible heater was also wired through a thermostat which activated the heater only when the water
temperature dropped below 1.6 °C and deactivated the heater when the water reached 10 °C. During non-winter
months the tank heater, along with the pump box heat source and insulation, were removed.
17
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Figure 4-7. Graywater storage tank, pump, and piping system used to collect graywater from the dormitory.
With the addition of supplemental dormitory graywater, average inflow rates were set to approximate the low-load
graywater flow estimated for a single-family household. Although the wetland was not explicitly designed for
residential use, there exists great potential to transfer the current design to residential applications. Thus, since hauling
water from the dormitory allowed for a specific inflow rate to be maintained, that flow rate was set approximately to
the expected flow from a single-family household. The desired influent rate was computed using the per capita water
uses presented in Mayer et al. (1999), which established an average indoor water demand of 262 L/d/person. Without
considering the demands of toilets, dishwashers, and cloth washers, indoor demand was reduced to 132 L/d/person.
This portion was considered the quantity of indoor demand which generates low-load graywater. Multiplying the low-
load graywater generation rate by an average population per household of 2.6 (U.S. Census, 2000) gave an influent
rate of 343 L/d.
18
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Figure 4-8. Trailer-mounted tank used to haul dormitory graywaterto the wetland system.
Figure 4-9. Metering pump in insulated box used to transfer dormitory graywater from trailer-mounted tank to wetland system.
Influent Composition
The graywater inflow to the wetland varied by season due in part to differing compositing methods. During winter
months (December through February), only dormitory graywater was supplied to wetland, as the 300 L composite
tank and ACB source water was taken off line to prevent it from freezing, and inflow samples were instead drawn
directly from the heated, trailer-mounted tank. It should also be noted that during January, 2009, graywater was
provided from a single-family, residential household for approximately 12 days when dormitory graywater became
19
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unavailable during the CSU winter break. In all other seasons, the 300 L composite tank was utilized, and both
dormitory and ACB graywater were mixed and provided to the wetland.
During the summer of 2009, a large quantity of rainfall was followed by a long period of high temperatures and
increased evapotranspiration. The result was an initial period of high flows, followed by nearly no flow the remainder
of the summer to the second cell despite supplementing dormitory and the ACB influent with residential water in an
attempt to overcome high ET rates. Higher graywater flow rates from the ACB were observed during the spring
season than initially observed in the fall season. Thus, less dormitory graywater was used during the spring season
than the fall season to achieve the same composite flow rate.
Flow Monitoring
Flow meters were installed in each manhole, and provided measurements of the inflow and outflow rates of each
wetland. The inflow rate, measured in Manhole #1 (Figure 4-1), was taken downstream of the point where graywater
from the ACB and dormitory was mixed. Flow rates throughout the system were highly variable, and were observed
to range from less than 4 L/d when the ACB was unoccupied and no dormitory graywater was being dosed, to over
1,000 L/hr during periods of intense precipitation. To accommodate a wide range of flows, as well as high solid
contents, a dosing flow meter system was devised.
Flow Meter Design
In each manhole, flow collected in a 5.7 L plastic dosing vessel, denoted by "A" in Figure 4-10. When full, a multi-
level float switch activated a submersible pump, "B" and "C", respectively, which pumped the flow out of the dosing
vessel and through a 20-mm diameter turbine flow meter (Great Plain Industries TM100-N, Wichita, Kansas),
denoted "D" in Figure 4-10. A course, 1-mm inline strainer, marked "E" in Figure 4-10, was inserted upstream of
each turbine meter to prevent turbine damage. A second float switch, denoted "F", was installed on the dosing vessel,
which activated a counter (Red Lion Controls CUB-1, York, Pennsylvania) each time the vessel filled and emptied.
This counter provided measurement redundancy since the approximate volume pumped per dose remained fairly
constant throughout the experiment.
The turbine meter was orientated vertically to prevent water from standing in the turbine casing as stagnant water
promoted biofilm growth on the turbines, which in turn affected meter accuracy. In fact, all plumbing in the manholes
was done in a manner to minimize any standing water throughout the system. Straight pipe runs of 200 mm (10 times
the inside diameter of the turbine meter) were installed both up- and down-stream of each turbine meter per
manufacturer's instructions to measure flow more precisely.
Flow metering systems were self-contained, and powered by 12 V batteries. Since they were located in damp
manholes, all electronics were sealed and isolated. An overflow in each dosing vessel was provided in the event a
battery died or a pipe obstruction occurred. Vents and check valves were also provided in the metering system to
prevent siphoning and backflow, respectfully. Batteries required replacement and recharging approximately every
5,500 to 7,500 L of transferred water or 14 days, whichever came first. Although larger batteries would have allowed
for fewer recharges, size and weight limitations were imposed on the batteries, since they were frequently lowered
into relatively deep manholes.
Flow Rate Determination
The turbine flow meters gave cumulative or totalized volume readings, which were recorded approximately three
times a week throughout the experiment. Cumulative volumes were divided by the length of time between readings to
yield averaged flow rates as given in Equation 4-1.
20
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A - dosing vessel
B - float switch
C - submersible pump
D - flow meter
E - mime strainer
F - second float switch
Figure 4-10. Flow meter design.
Equation 4-1
Where: tj = the time that the flow reading was taken (hr)
tj.i = the time that the previous flow measurement was made (hr)
Vj = the cumulative volume read from the flow meter at tj (L)
Vj.i = the cumulative volume read from the flow meter at tj.i (L)
= the mean flow rate between tj.i and tj (L/hr)
The cumulative volumes were also divided by the number of counts (one count equaled one dose of the vessel) to
yield an average volume/dose. This value was observed to remain fairly constant, and was therefore used to alert any
potential malfunction of the flow metering system. Malfunctions typically arose from biofilm growth on the turbine
meter impellers, which required that the meters be cleaned and recalibrated approximately every 8 weeks.
21
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Water Quality Analysis
Water quality sampling was conducted to evaluate the treatment efficiency and effluent concentration of the wetland
for common organic, nutrient, solid, pathogen, and surfactant constituents. The treatment effectiveness and effluent
quality of each wetland bed and the system as a whole was determined through the implementation of a systematic
sampling plan. This sampling plan was developed within a quality assurance project plan (QAPP) prepared for and
approved by the EPA. For sake of review, a generalized overview of the sampling plan is provided in this section,
along with sampling location and frequency and data analysis methods.
Sampling Locations
Water quality measurements were made at three locations (Figure 4-11):
1. The influent, or inflow to the FWS system
2. The FWS effluent, or between the FWS and SF
3. The SF effluent, or SF system outflow
These locations were chosen because they represented the inflows and outflows of each wetland bed, thereby
allowing evaluation of each bed independently and the system as a whole. During spring and fall months, influent
grab samples were taken from the 300 L composite tank and represented approximately a daily composite. During
winter months, influent samples were drawn directly from the 1,800 L trailer-mounted tank and represented
approximately a 72 hour composite. FWS and SF effluent samples were drawn from the dosing vessels of the flow
meter in manhole #2 and #3 respectfully. Effluent samples from the FWS and SF were not composited under the
assumption that appropriate mixing occurred in each bed prior to outflow.
1) Influent
2) FWS Effluent
3) SF Effluent
Composite
Tank
Figure 4-11. Water quality sampling locations.
Analyzed Parameters
Samples were analyzed for temperature, pH, turbidity, DO, SC, TOC, BOD5, TN, NH3, NO3", TP, PO43", Cl", SO42", E.
coll, TSS, TDS, TVS, VSS, and anionic surfactants. These parameters were chosen as they represent a detailed
assessment of the overall effluent water quality, specifically for irrigation reuse applications. Also, the wide range of
constituents measured gave a good assessment of the treatment efficiency of the graywater wetland on organics,
nutrients, solids, and pathogens.
Physio-chemical Parameters: Turbidity, pH, DO, and SC were measured since all are common metrics of water
quality and these measurements relatively inexpensive and readily available. Both pH and turbidity are standards
given in the urban reuse regulations (EPA, 2004) and SC provides a good indication of water salinity, which is
valuable to know for irrigation purposes given that some plants have low salt tolerances.
Organics: Both BOD5 and TOC are a measure of the organic loading in wastewater, and are used to indicate the
overall water quality biotic suitability of environmental systems. Specifically, BOD5 is often cited as a water quality
standard in regulations.
22
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Nutrients: Both TN and TP were chosen for measurement since they provide cumulative macronutrient contents. In
addition, NH3 and NO3" were chosen since they typically represent the bulk of soluble nitrogen in environmental
waters. Initially, NO2" was also measured, but was discontinued due to concentrations consistently below detection
limits.
Solids: Solids were measured as they can negatively affect water quality and reuse applications. Initially, only TSS
was analyzed since it is this category of solids that typically clogs irrigation systems. Later, TDS analysis was added
to verify SC values. Algal growth can be assessed by VSS which is a simple addition to the TSS and TDS analyses.
Surfactants and Anions: Surfactants were measured out of concern of bioaccumulation and toxicity of degradation
byproducts and since little prior research has examined their degradation in graywater through constructed wetlands.
Specifically, anionic surfactants were examined as they are the most commonly found surfactants in body soaps and
other personal care products. The levels of Cl", a conservative constituent, were useful in tracing the flow additions
and losses.
Pathogen Indicators: E. coll was chosen as the routinely measured fecal indicator bacteria since it is a very specific
indicator of pathogenic bacteria, and since the Colorado Department of Public Health and Environment (CDPHE) is
moving towards using E. coll as its sole pathogen indicator (CDPHE, 2007). Although other routine microbial testing
was desired, such tests were cost prohibitive.
Sampling Frequency
Sampling frequency was determined by analyzing the costs of various sample packages at various sampling
frequencies over a one year. Note that while the aforementioned measurements were justified from a water quality
perspective, budget constraints yielded the ultimate decision as to which constituents were measured. Based on the
desire to analyze a wide range of parameters over an extended period of seasonal variation and the available budget, a
sampling frequency of every three weeks was selected.
Analysis Methods
As described in the QAPP, Standard Methods (SM) (APHA et al., 1998) were used for all water quality analyses
except anionic surfactants. Temperature and DO were analyzed in the field using a membrane electrode (Yellow
Springs Instruments DO200, Yellow Springs, Ohio). Both pH and NH3 were analyzed using an ion selective electrode
(Thermo Scientific Orion 25OA, Waltham, Massachusetts). Turbidity was measured with a nephelometric
turbidimeter (Hach 2100N, Loveland, Colorado). Both TOC and TN were analyzed via combustion of acidified
samples (Shimadzu TMN1, Columbia, Maryland). An ion chromatograph (Metrohm Peak 861, Herisau, Switzerland)
was used to measure NO3", PO43", Cl", and SO42". E.Coli were quantified via enzyme substrate (Idexx Laboratories
Colilert/Quanti-Tray/2000, Westbrook, Maine). Anionic surfactants can be measured using a methylene blue active
substances (MBAS) method (SM 5540C). This method, considered to be a broad estimation of all anionic surfactants,
has been compared to other methods, such as the crystal violet method available through Hach, with the intention of
finding a simpler method of determining anionic surfactants. Although all methods have shown some susceptibility to
interference, other methods, including crystal violet, have been validated (Cross, 1998). Thus, anionic surfactants
were analyzed by extraction of surfactant/crystal violet dye ion-pair complexes into benzene following the procedure
of Hedrick and Berger (1966) and using a commercial surfactant testing kit (Hach Kit #2446800, Loveland,
Colorado). The crystal violet method available from Hach measures surfactants that include an aromatic ring in their
chemical structure, i.e., LAS and alkyl benzene sulfonate (ABS). Through electrophilic aromatic substitution the
cationic, crystal violet dye bonds to the aromatic ring of LAS and ABS. When benzene is added to the solution a
similar reaction dissolves the surfactant/cationic dye product in the benzene, turning the benzene solution a violet-
blue color. MBAS uses methylene blue dye and chloroform to extract the surfactants and thus detection of a greater
number of anionic surfactant species is possible.
All other measurements, along with sample collection, preparation, and storage were conducted following standard
analytical methods (APHA et al., 1998). Quality assurance samples (e.g., blanks, duplicate analyses, and standards)
were analyzed throughout the experiment at a rate of 10%. Multiple replications (generally three) were used for every
23
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analysis when possible, and highest dilutions were always reported. In the case of bacterial samples, at least three
replications were made at every dilution.
24
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Chapter 5 Wetland Performance
Graywater influent characteristics, treatment efficiencies, and effluent quality all varied by season.
Results of wetland monitoring were evaluated seasonally as distinct sample populations, however, due to limited
seasonal data collection, statistical analysis by ANOVA was only performed on the complete data set (Table 5-5). The
potential for reuse was evaluated by comparing the seasonal effluent water quality to applicable regulations (Table
3-3 and Table 3-4). The treatment efficiency of each wetland bed, and the system as a whole, were evaluated in terms
of pollutant mass removal.
Water quality sampling and flow measurement commenced in September, 2008 and continued until August, 2009. At
the onset of sampling, sampling events were conducted on a weekly basis for four weeks, after which samples were
collected every three weeks on average. Initially, sampling was conducted weekly to establish equilibrium conditions
following wetland startup. Wetland startup was an approximate three week period in September, 2008, immediately
following the point when dormitory graywater became available. Prior to this time, graywater from the ACB was
supplied to the FWS, but due to low flow rates, tap water supplemented the greywater feed to the SF. To flush the tap
water and allow the wetland to come to equilibrium with dormitory graywater, sampling of the FWS and SF effluents
were postponed 7 and 15 days after dormitory graywater was first supplied to approximate HRTs of the beds
respectively.
Treatment Efficiency Determination
Simple comparison of the influent and effluent water qualities may not adequately evaluate the treatment performance
of the wetland system because the effects of flow additions and losses on the effluent concentrations are not
considered. However, by computing the mass loading at each point in the wetland, the effects of flow additions and
subtractions are abated. In other words, comparing pollutant mass flux through the system instead of pollutant
concentration changes resolved the dilution effects of precipitation and the concentration effects of ET.
Treatment efficiency, or mass removal, was computed by the average difference in mass loading between the influent
and effluent of each wetland bed. Mass removals were considered seasonally, and were computed using the average
mass loading over a season for the influent and effluent of each bed (Equation 5-1). Mass loading equals the product
of flow rate and concentration, and was averaged seasonally using the measured concentration and the average flow
rate over one HRT preceding the sampling event for all sampling events within a season (Equation 5-2). Influent
loading rates considered the HRT of the FWS. FWS and SF loading rates considered the HRT of the SF. Flow rates
were averaged over one HRT since that is the length of time over which flow rates affect the HRT, and therefore the
wetland treatment efficiency. Because flow rates determine HRT, the calculation of an average flow rate over one
HRT was performed iteratively.
25
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TE =
HI Influent ~ HI Effluent
xlOO%
Equation 5-1
ITllnfl,
luent
T i(c,*<0
m =
n
Equation 5-2
Where:
TE = treatment efficiency of a given system or bed for a particular season
m = mean mass loading rate over a given season for a particular influent or effluent (mg/season)
n = number of sampling events in a given season
C; = concentration of an influent or effluent for sampling event /' (mg/L)
= mean daily flow rate (L/d)
Hydrologic Performance
Flow Characteristics
Flows to and through the wetland varied by month and by season (Table 5-1 and Figure 5-1), and were influenced by
the source and availability of graywater, losses from groundwater seepage and ET, and precipitation additions.
Runoff intrusions were prevented via the protective berm surrounding each bed. Inflow rates fluctuated in response to
seasonal variations in the graywater quantity generated from the office/laboratory building. In addition, during winter
months, access to dormitory graywater was restricted, and the inflow rate was reduced accordingly. Seasons were
defined as initial measurements in September through November for fall, December through February for winter,
March through May for spring and June through last measurements in August for summer.
Table 5-1 Seasonal Mean Flow Rates and Standard Deviations
Season
Fall
Winter
Spring
Summer
Mean Flow ± s (L/d) (coefficent of variation )
Influent (I)1
334 ±33 (0.10)
247 ± 106 (0.43)
303 ±119 (0.39)
276 ± 152 (0.55)
FWS Effluent (2)
285 ± 86 (0.30)
214 ±105 (0.49)
305 ± 220 (0.72)
273 ±249 (0.91)
SF Effluent (3)
264 ± 86 (0.32)
206 ±111 (0.54)
320 ± 275 (0.86)
111 ±183 (1.65)
Number refers to location in Figure 4-11.
26
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I Influent (1) Free water surface effluent (2) Subsurface wetland effluent (3)
Spring
Summer
Season
Winter
Figure 5-1. Seasonal averaged flow rates in the wetland system.
Water losses due to ET and seepage were large, especially ET during summer months, and were the cause of losses
through the system and the decreasing flow rates out of the SF cell. Seepage occurred up and over the impermeable
wetland liners in both wetland cells, which resulted from an inadequate elevation difference between the water levels
and the top of the liners (this problem was discovered after the vegetation in the wetland beds was established, which
precluded altering the liner elevation). During the spring, frequent precipitation events caused FWS and SF wetland
effluent flow rates to be 1% and 6% greater than the average influent rate respectively. In the summer, several large
precipitation events and varying inflow rates caused the average FWS effluent flow rate to be almost as high the
average influent flow rate while very little SF effluent was observed due to high ET and evaporation rates. A record
of precipitation is included in Figure-1 in Appendix A. Rainfall data were collected from a Colorado Agricultural
Meteorological Network (CoAgMet) Class A weather station located approximately 650 m from the wetland.
Summer conditions were much more variable than the other seasons due to weather conditions and insufficient
graywater coming from the dormitory and ACB. As mentioned previously, after a period of high precipitation and
cool temperatures, the weather changed dramatically bringing high temperatures and nearly no precipitation. During
this time there was also little water coming from the dormitory or the ACB, so graywater (including shower/bath
water, laundry water, and hand wash water) from a residential source in Fort Collins, CO was used. Despite this extra
water, very little effluent was collected from the end of the system. To fill the collection bucket, a section of tubing
was lowered. Once enough water was available for collection, the tubing was returned to its original position. The
flow meters and counters showed that very little water flowed out of the second cell of the wetland during the summer
months. Except during spring months, inflow rates were larger than FWS or SF effluent rates. As shown in Figure
5-1, large deviations between the desired and actual inflow rates occurred during winter months when dormitory
graywater collection was restricted.
27
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Hydraulic Retention Time
The HRT was calculated by dividing the mean seasonal volume by the mean seasonal flowrate. The HRT in each
wetland bed varied with seasonal flow conditions (Table 5-2), and were also affected by bed volume fluctuations in
the winter resulting from ice coverage. Ice thickness was measured approximately twice weekly throughout the
winter, and was considered in volume computations. During the 2008/2009 winter, a maximum ice thickness of 170
mm was observed on the FWS, while the gravel matrix in the SF provided insulation such that the maximum ice
thickness was only 38 mm (Table 1 Appendix A). While the winter ice reduced the volume of each cell, reduced flow
rates during winter months resulted in the higher observed HRTs than spring and fall. HRTs were lowest during the
spring, largely because of frequent precipitation and were highest during the summer because of infrequent
precipitation and reduced influent. Precipitation was treated simply as an additional inflow, which reduced overall
HRT.
Table 5-2. Seasonal Mean Hydraulic Retention Times and Standard Deviations
Season
Fall
Winter
Spring
Summer
Mean Hydraulic Retention Time (d)
FWS Effluent (2)1
7.0
6.4
6.6
7.3
SF Effluent (3)
9.9
12.4
8.1
23.5
Total
16.9
18.8
14.7
30.8
Number refers to location in Figure 4-11.
The HRTs observed in the wetland were six to ten times greater than those published for other constructed wetlands
used to treat graywater. For example, the wetlands presented by Winward et al. (2008b) and Gross et al. (2007b) both
featured HRTs that were maintained nearly constant at approximately two days. Near constant HRTs are typical of the
treatment wetlands presented in the literature, but were not the case with the graywater wetland, which experienced
large seasonal fluctuations in HRT. Of note is that the wetland studied here was designed for contaminant removal
during the cold winter months observed in Fort Collins, CO. The HRTs observed in the wetland are longer than the
HRTs of constructed wetlands used in wastewater treatment which typically range from one to six days (EPA, 1993).
Water Quality Results
The subsequent section provides water quality results and statistics from 18 sampling events conducted between
September, 2008 and August, 2009. Unabridged water quality data and statistical analysis are presented in Appendix
A. The seasonal and annual results for water quality parameters are presented using boxplots, created using Microsoft
Excel. Boxplots allow condensed data statistics to be displayed, and show the following statistics of a population:
median, range, and lower (1st) and upper (3rd) quartiles. Significant differences in water quality between influent and
effluent concentrations were examined using one-way ANOVA at P < 0.05. Statistics on significance are provided
only for the complete data set. Due to the low number of seasonal data points (which is denoted by "n" for number of
date points), statistics are not provided seasonally.
Physio-chemical Parameters
The physio-chemical properties of the raw graywater influent and the effluent of each wetland bed varied seasonally.
SC and turbidity results are segregated seasonally and are presented in Figure 5-2 and Figure 5-3, respectively.
Seasonal averages, standard deviations (s), and measurement ranges of temperature, DO, and pH are subsequently
included in Table 5-3.
28
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29
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Table 5-3. Seasonal Mean Physio-chemical Parameters Measured in the Greywater Wetland.
Influent
Analysis
Temp
(°C)
DO
(mg/L)
pH
Parameter
Mean± s
Range
Mean± s
Range
Range
Fall
12.6 ±3.7
5.9-17.6
0.11 ±0.05
0.02-0.2
6.0-6.6
Winter
16.0 ±5.4
11.3-21.9
0.08 ±0.03
0.05-0.1
6.6-6.8
Spring
7.8 ±6.4
0.4-16
0.3 ±0.21
0.14-0.62
6.2-6.4
Summer
18.9 ±1.4
17.5-20.7
0.3 ±0.23
0.08-0.53
6.2-6.8
Free Water System Effluent
Submerged Flow Effluent
Analysis
Temp
(°C)
DO,
(mg/L)
pH
Parameter
Mean± s
Range
Mean± s
Range
Range
Fall
11.3±3.1
7.8-15.1
3.2 ±1.6
1.3 -5.5
6.6-6.9
Winter
4.4 ±3.0
2.5-7.8
1.2 ±0.06
1.1-1.2
6.4-6.7
Spring
7.7 ±2.8
4.7-11.5
4.7 ±2.3
1.7-6.7
6.5-6.8
Summer
16.8 ±0.55
16.1 -17.3
1.1±0.4
0.71 - 1.64
6.5-7.1
Analysis
Temp
(°C)
DO,
(mg/L)
pH
Parameter
Mean± s
Range
Mean± s
Range
Range
Fall
12.4 ±3.2
8.6-16.3
2.4 ±0.6
1.4-3.0
6.3-6.8
Winter
5.2 ±4.5
1.9-10.3
2.2 ±0.2
2.1-2.4
6.5-6.7
Spring
9.0 ±3. 9
4.5-14
2.5 ±0.5
1.8-2.8
6.1-6.6
Summer
18.9 ±1.2
17.8-20.6
1.7 ±0.3
1.3-2.1
6.3-7.3
Note: n = 7 (fall), 3 (winter) and 4 (spring and summer)
Average SC values increased through the wetland for all seasons ('through the wetland' implies from the influent to
the FWS effluent and from the FWS effluent to the SF effluent), indicating that dissolved solids and/or salts were
likely accumulating in each wetland bed. Accumulation of dissolved ions can be common in wetland systems and
results primarily from evapotranspiration. Conversely, precipitation contains relatively little dissolved solids, and
would be expected to lower the SC in the wetland beds. This is evident by the relatively lower increase in the SC
through the wetland system in the spring season which was the rainiest season observed.
Regardless of accumulation, measurements indicated that the wetland effluent SC was less than 350 uS/cm for any
season, rendering the effluent water as "good" (Table 5-4) for irrigation based on SC levels recommended by FCES
(2004). Furthermore, SC readings of the raw graywater influent were generally less than either bed's effluent,
indicating that salinity levels in the low-load graywater were also suitable for irrigation. Influent SC values were in
line with those given in Eriksson et al. (2002).
30
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Table 5-4. Recommended Specific Conductivity Levels (FCES, 2004)
Class of Water
Excellent
Good
Permissible
Doubtful
Unsuitable
Specific
Conductivity, uS/cm
<250
250-750
750-2000
2000-3000
>3000
Turbidity measurements decreased through the wetland for all seasons except for summer. Percent reduction (by
measurement, not mass) between the influent and SF effluent ranged from 69% in the fall to 83% in the spring. The
mean turbidity of the system effluent was approximately 6 NTU during the fall and spring, and nearly 17 NTU during
the winter. Summer effluent results from the FWS cells were comparable to results from the fall (~10 NTU) but SF
effluent results were about twice that of the fall results. Much of the solids during this time were thought to be from
biofilm disturbed by the change in collection methods and algae that was present in the FWS earlier in the season
moving through the system. VSS concentrations were slightly higher in the SF effluent during the summer (nearly 7
mg/L in the summer compared to about 4 in the winter and spring) but as a percentage of TSS, VSS were actually
lower (50%, 63%, 60%, 43% for summer). The solids present in SF effluent in the summer months were largely
inorganic in nature and it is difficult at this time to determine the source of inorganic solids from the SF cell. This will
be examined with future sampling efforts at the constructed wetland. Unrestricted reuse guidelines for several states
(e.g., Arizona, California, and Washington; see Table 3-3) give maximum and average turbidity values of 5 NTU and
2 NTU respectively. The EPA (2004) also gives turbidity recommendations of 2 NTU for reclaimed water used for
irrigation. Under these strict regulations, the wetland effluent would be out of compliance for use as unrestricted
irrigation water.
Reuse regulations also stipulate an acceptable pH range between 6 and 9 (EPA, 2004). The effluent pH ranged
between 6.14 and 7.26 throughout the year, which is acceptable for reuse. Despite this range, the pH remained fairly
constant (around 6.5) for all measurement locations through all seasons. The DO of the influent was quite low,
indicating anaerobic conditions of the stored graywater. DO generally increased through the wetland system, with the
highest DO measured during spring and fall seasons in the FWS effluent. This was likely due to the open water nature
of the FWS, which probably promoted more oxygen transfer than the closed surface nature of the SF. DO at the FWS
effluent was very low during winter months, explained by the thick ice cap on the FWS which prevented atmospheric
contact. DO was also low in the FWS effluent during summer months. It is possible that extensive growth of plants in
the FWS resulted in decreased oxygen transfer into the cell during this time period. Temperature through the wetland
generally remained constant in the fall, decreased in the winter, and increased in the spring and summer. The high
influent temperature in the winter is partially attributed to the submersible heater in the trailer- mounted tank.
Organics
Organics, measured by BOD5 and TOC decreased substantially though the wetland for all seasons - see Figure 5-4
and Figure 5-5, respectively.
31
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Biochemical Oxygne Demand - Five Day (mg/L)
K)
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Influeni
o
q FWS Efflueni
£-
t
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SF Efflueni
n = 7 (fall), 3 (winter, spring and summer influent and FWS effluent) and 2 (summer SF effluent)
Figure 5-5. Plotted box plots for total organic carbon.
32
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Influent concentrations of BOD5 and TOC were common to those given in literature (Erikkson et al., 2002 and
Cassanova et al., 2001). Effluent concentrations of BOD5 were lowest in the fall (3.1 mg/L) and highest in the winter
(45.6 mg/L). Only during the fall and summer were effluent BOD5 levels below the state mandated (from Table 3-3)
and EPA (2004) recommended level of 10 mg/L for urban reuse of reclaimed water. The treatment efficiency (percent
removal by mass) of BOD5 through the wetland was greater than 89% throughout the year, with removal rates of
96%, 92% and 94% observed during fall, spring and summer seasons respectively (Figure 5-6). Lower removal
efficiencies during winter months, 80%, were primarily attributed to lower temperatures.
Similarly, average effluent TOC levels were lowest in the summer (7.53 mg/L), but were greatest in the spring (22.17
mg/L). TOC removal rates were less than BOD5, but always remained greater than 50% (Figure 5-6). This indicates
that removal of readily biodegradable organic material, as measured by BOD5, is effective through the wetland.
However, there are likely recalcitrant organics (e.g., degradation byproducts, soluble microbial products, or plant
exudates) that are not as readily removed through the wetland system. During spring months, TOC removal was
particularly low in the SF. This low removal efficiency in the spring is partially explained by the increased effluent
flow rates resulting from precipitation, which increased the computed mass loading at each effluent location. As
evident in Figure 5-6, a majority of BOD5 and TOC was removed in the FWS - although the HRT of the FWS was
less than the HRT of the SF, the FWS was first in series and was likely the location where the bulk treatment of
readily biodegradable organics occurred.
The dissolved portion of total organic carbon - dissolved organic carbon (DOC) was also measured periodically.
DOC decreased through the wetland system similarly to TOC, with DOC concentrations being approximately 50% to
75% of TOC levels. Removal of DOC was less than TOC for most seasons except summer.
n FWS Effluent D Total Effluent
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DOC
Winter
t
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-
-
TOC
Spring
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DOC
BOD
i-
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DOC
Summer
Figure 5-6. Percent organic removal efficiencies.
33
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Nutrients
Nitrogen was evaluated via TN, NH3, and NO3". Results of TN and NH3 monitoring are given in Figure 5-7 and
Figure 5-8, respectively. Observed concentrations of NO3" were below or near the detection limit for all measurement
locations and for all seasons except for one measurement during the summer at the influent and at the SF effluent
during the fall and summer, when the average NO3" was 0.24 mg/L. The detection limit for NO3", as well as PO43", Cl"
and SO42", was 0.2 mg/L. This was the lowest discernible concentration obtainable from the ion chromatograph,
which was used to measure anions.
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Figure 5-7. Plotted box plots for total nitrogen.
34
-------
35 T
n = 7 (fall influent), 6 (fall FWS effluent), 5 (fall SF effluent), 4 (summer all sites) and 3 (winter,
Figure 5-8. Plotted box plots for ammonia.
NH3 represented 40% to 65 % of the TN measured in the influent throughout all seasons, with both parameters within
published ranges for raw graywater (Eriksson et al., 2002). At the effluent of the FWS and SF, the ratio of NH3:TN
was variable, but generally lower than the influent, indicating biotic uptake of soluble ammonia. Average
concentrations of TN and NH3 in the wetland effluent were highest in the winter (7.1 mg/L and 5.0 mg/L respectively)
and lowest in the summer (0.84 mg/L and 0.4 mg/L). These effluent nitrogen levels, especially for NH3, are quite high
with regard to toxicity levels in freshwater. General EPA freshwater guidelines for NH3 depend on temperature, pH,
and the type biotic organisms present (EPA, 1986). This reference gives applicable total ammonia limits between 1.5
mg/L (at 20°C, pH = 6.5, salmonids present) to 2.4 mg/L (at 5°C, pH = 6.5, salmonids absent). Except during fall and
summer months, the effluent levels of NH3 could be toxic to freshwater biota, which should be considered if the
effluent were to be stored in or directly released to an environmental water body. However, if the effluent is applied
directly for irrigation, high NH3 concentrations should be of little concern. In fact, high levels of NH3 and TN may in
fact be beneficial to the landscaping receiving the effluent for irrigation. Limits for nitrate depend on end use,
Drinking water supplies have NO3" limits of 10 mg/L, while toxicity levels for salmonid species have been shown to
be between 0.6 mg/L and 1.6 mg/L, and toxicity levels for warm water, i.e., not salmonid species, are greater than 10
mg/L. As discussed, the graywater wetland had effluent concentrations of NO3" less than 0.24 mg/L for all seasons,
keeping the effluent well within NO3" regulations for all end uses.
Concentrations of TN and NH3 were reduced through the wetland for all seasons, except through the SF during the
spring (Figure 5-9). During the spring, the NH3 concentration increased through the SF. This concentration increase
was consistently observed for all sampling periods during the spring, and may have resulted from increased algae
uptake of ammonia in the FWS and subsequent nitrogen release from decomposing algae or detritus in the SF.
35
-------
1FWS Effluent D Total Effluent
100
OS
s
o
I
80
60
40
20 --
Nitrogen
Spring
Ammonia
Nitrogen
Summer
Figure 5-9. Percent nitrogen removal efficiencies.
As noted NO3" were low, even for influent values and were lower than literature values (Table 3-1). The
concentrations of NH3 influent values were a mean of 5 mg/L or greater for all seasons and theses values were higher
than the characteristic literature values (Table 3-1) which were all < Img/L. The low NO3" and high NH3 values are
potentially an indication of biological activity and nitrogen conversion. Rose et al. (1991) noted the increase in NH3
and PO43" may be due to nutrients available for microorganisms. This is discussed further under the sub heading
Surfactants.
Phosphorus was measured by TP and PO43" (Figure 5-10 and Figure 5-11). PO43" concentrations were always below
detection (0.2 mg/L) at the SF effluent for sampling events except for one summer event. During the spring, all PO43"
measurements at all sites were below detection. Along with SF effluent samples, several PO43" measurements in FWS
effluent were also below detection. For the sake of comparing concentrations above and below the detection limit,
PO43" concentrations below the detection limit were assumed to be half the detection limit (or 0.1 mg/L) when
computing seasonal concentration averages and percent removals (Figure 5-12) during fall and winter seasons.
36
-------
Q
8"
7 :
OD :
£ 4 :
W
1 3:
OH
W
O 'S
CM :
3 ! :
! r
; t
: -^.
: EJ
; ft [
: X t
]
§ § §
G ^ S
« w w
GO PH
f£ GO
PH
Fall
1
--
§
G
.
.
1
w
GO
PH
Winter
?
3-1
3
' -t
SF Efflueni
G
}-
1
W
GO
PH
Spring
#
SF Efflueni
!> I
* *
s § s
s s s
^ S F^
rt M-H S-H
» i W W
OO PL,
^ ^
PH
Summer
'"" fl
T 5
s § s
ill
GO PH
f£ GO
Overall
n = 7 (fall influent), 6 (fall FWS effluent), 5 (fall SF effluent), 4 (summer all sites) and 3 (winter and spring all sites)
Figure 5-10. Plotted box plots for total phosphorus.
37
-------
oo
1)
D
£
A
n
_L '
|
; £ ' [t] PI ^
; "^Q^^U?-1!,
rtggrtggrtggsg
GO PH GO PH GO PH GO
Winter Spring Summer Fal
5
D D
SCn CH CH
1) 1) 1)
^ ^ ^ £
w 5 w w
PH GO PH
GO > GO
PH
Overall
n = 7 (fall influent), 6 (fall FWS effluent), 5 (fall SF effluent), 4 (summer all sites) and 3 (winter and spring all sites)
Figure 5-11. Plotted box plots for phosphate.
TP and PO43" concentrations in the influent were reasonable compared to literature values (Table 2.1). Approximately
45 - 55% of influent total phosphorus was in the dissolved phosphate form. This percentage dropped to 10 - 30% in
the FWS effluent and to less than 9% in the SF effluent, showing that phosphate was quickly metabolized in the
wetland. Treatment efficiencies of phosphate were very high (> 90%), but less so for total phosphorus, especially
during colder, winter months (Figure 5-12). As mentioned, in the spring, influent and effluent phosphorous
concentrations were below detection limits so no loadings were calculated.
38
-------
1FWS Effluent D Total Effluent
100
S 80
.c
"«
k
o
D
05
40
20
Figure 5-12. Percent phosphorus removal efficiencies.
Solids
Initially, only TSS were analyzed. Starting in November, 2008 dissolved, volatile, and fixed solids were also
measured. Seasonal TSS measurements are shown in Figure 5-13, and TDS measurements are shown in Figure 5-14.
Volatile and fixed contributions to each seasonal suspended and dissolved solids category are shown in Figure 5-15.
39
-------
30 -
25 -
20 -
00
M 15 -
13
ispended Sol
o
GO
O
H
0 -
J «n
I
a
d
i
_
j~"; f|
1 1 ±
..
4) 4) 4) u 4)
2 2 2 2 2
s a
-------
o
GO
Q
3
o
H
300
250 --
200 --
150 --
100 --
50 --
nflue
£
w
GO
I
I
w
PH
GO
nflue
Winter
n = 3 (winter and spring) and 4 (summer)
£
w
GO
Spring
w
PH
GO
nflue
s
w
GO
PH
Summer
Efflue
nflue
GO
PH
Overall
Figure 5-14. Plotted box plots for total dissolved solids.
41
-------
o
GO
250 -
200 :
150 :
100 -
50 -
0 -
;f
3
s
G
£
1
s
w
GO
PH
Winter
i
m
3
-P
" 1 1
. " y i ^
1
s
w
PH
GO
§ § s § s
1 1 1 1 1
M W W M W
GO PH GO
f£ M ^
PH PH
.
-
i
£
w
PH
GO
Spring Summer
1
^
s
£
w
GO
PH
1
£
w
PH
GO
Overall
n = 3 (winter and spring) and 4 (summer)
Figure 5-15. Plotted box plots for total volatile solids.
TSS concentrations were reduced substantially between the influent and SF effluent for all seasons other than
summer, producing mean effluent concentrations of less than 4 mg/L for spring and fall, and less than 7 mg/L during
winter months. Effluent TSS would meet even the strictest state or EPA reclaimed water regulation (5 mg/L) for
irrigation during the fall and spring seasons. Even during the winter, effluent TSS was below EPA recommendations
and most state regulations (except Florida) for irrigation water. However, effluent TSS was high in the summer
months in comparison to other seasons even while TSS in the FWS cell was low (Figure 5-13).
The SF cell actually contributed solids during the summer. It is hypothesized that an extensive biofilm formed on the
gravel present in the SF cell over summer months and the biofilm sloughed into the water, thus contributing to TSS.
However, unlike the rest of the year when percent VSS in the SF effluent was between 50 and 60%, the percentage of
VSS in the SF effluent during the summer was only 43%. At this time, it is difficult to determine the source of
inorganic solids in the SF cell. Nonetheless, there was an overall decrease in TSS through the wetland during summer
months despite the mean effluent concentration of nearly 16 mg/L. No substantial difference was observed in TSS
concentrations between the influent and FWS effluent during spring or fall months. In fact, during these seasons FWS
effluent TSS was often higher than the influent, which is attributed to the large amount of algae growing in the FWS.
Algae in the FWS were especially plentiful immediately following ice-off in the spring. For approximately two weeks
after the ice melted, thick algae blooms were observed in the FWS.
TDS contents fluctuated widely between every sampling event. Considering the observed s of the box plot (Figure
5-14), no significant difference was observed between the three measurement sites during any season. Surprisingly,
TDS measurements did not correlate well with SC measurements as would be expected. The ratio of TDS:SC varied
widely within sites and seasons, and ranged from 0.1 to 1.2 with a mean of 0.6. This mean TDS:SC ratio was within
the common range of wastewater and those given by Eriksson et al. (2002) for graywater.
42
-------
Dissolved solids were greater than TSS for all samples, and generally the volatile (organic) portion of the solids
exceeded the fixed (inorganic) portion. It was also found that for fall and winter months, the volatile fraction
decreased and the fixed fraction increased through wetland (this is especially clear during the winter months). Much
larger fractions of volatile suspended solids were seen in the FWS effluent as compared to the SF effluent, which is
again attributed to algae in the FWS.
Even though TSS influent concentrations were lower than the range of graywater values from the literature (Table
3-1), i.e. < 54 mg/L, mass removals were consistently high. Total mass removals of TSS were greater than 75%, with
the highest removals realized during winter months (Figure 5-16). Even though TDS concentrations changed little
between the influent and effluent, overall percent removals were positive, and resulted primarily from changes in
mass loading due to differing flow rates (Figure 5-16).
1 FWS Effluent Total Effluent
100
80
.c
"«
k
o
E
40
20 --
TSS | TDS | TVS
Fall
TSS TDS TVS
Winter
T-
l_
TSS | TDS TVS
Spring
TSS TDS | TVS
Summer
Figure 5-16. Percent suspended, dissolved, and volatile removal efficiencies.
Anions
Seasonal anion (Cl~ and SO42") concentrations are shown below in Table 5-5. Cl" was evaluated mainly as a tracer
through the wetland. Concentrations of Cl" increased during winter, albeit slightly. During fall, Cl" decreased slightly
through the system. Spring Cl" measurements were made with incorrect dilutions, and all results except one were over
range (10 mg/L). Decreases in Cl" likely occurred due to precipitation additions, while Cl" increases were attributed to
ET. Likewise, SO42" generally decreased between the influent and the SF effluent, especially during the spring.
However, SO42" readings within seasons (especially the spring) generally had large variances resulting in very little
measurement difference between any sites for any season. Concentrations of Cl" in the inflow were within published
ranges, while SO42" concentrations were lower than those in the literature (Rose et al., 1991; Casanova et al., 2001).
43
-------
Table 5-5 Chloride and Sulfate Measurements and Statistics
Analyte
Parameter
Concentrations (mg/ L)
Fall
Winter
or Number (n) of Data
Spring
Points
Summer
Influent
cr
SO42"
Mean± s
Range
n
Mean± s
Range
n
9.6 ±0.8
8.9 - 10.9
7
11.6±3.4
5.3 - 16.3
7
10.2 ±0.7
9.4-10.9
3
7.4 ±0.8
6.8-8.3
3
12.2 ±4.4
10.0-18.8
4
9.6 ±4.8
6.1-16.1
4
8.4 ±5.0
1.1 -12.4
4
10.9 ±9.1
0.24 - 19.5
4
FWS Effluent
cr
so42-
Mean± s
Range
n
Mean± s
Range
n
9.6 ±0.9
8.6-11.0
6
12.6 ±2.4
10.6 - 16.8
6
11.1±0.7
10.7-11.9
3
9.8 ±0.7
9.2 - 10.5
o
J
11.4 ±2.7
10.0 - 15.4
4
4.81 ±3.7
0.2 - 8.2
4
6.4 ±4.8
0.51 - 10.54
4
9.3 ±5. 3
0.12=14.1
4
SF Effluent
cr
so42-
Mean + s
Range
n
Mean + s
Range
n
8.6 ±1.6
6.9-11.2
5
8.9 ±4.9
3.2-15.6
5
12.3 ±1.8
10.5-14.1
3
6.0 ±3.5
3.9-10.1
3
6.9 ±3.6
3.3 ->10
4
1.8 ±1.7
0.77-4.4
4
0.39 ±0.4
0.12-1.01
4
2.7 ±4.0
<0.2 - 8.5
4
Surfactants
Anionic surfactants were reduced substantially through the wetland treatment system, with SF effluent concentrations
being less than 1 mg/L for all seasons (Figure 5-17). Anionic surfactants include a wide class of molecular structures,
each with different molecular weights. Therefore, surfactant concentrations given below are normalized to the
molecular weight of linear alkyl benzene sulfonate (LAS).
Influent surfactant concentrations ranged from approximately 1-6 mg/L, which were less than the ranges given in
literature (Gross et al., 2007b). Influent concentrations were thought to be affected by the storage time of graywater in
the trailer-mounted tank, with lower concentrations resulting from increased storage time. To test this hypothesis,
biodegradation in the trailer-mounted tank was tested during the fall season by collecting samples as the tank was
filled and when the tank was nearly empty. Results of this one-time test showed a 49% reduction in surfactant
concentration in the trailer-mounted tank over 48 hours of storage. Incidentally, TOC and TN had reductions of 19%
and 6% respectively. Lower observed influent surfactant concentrations in comparison to published values likely was
due to the storage time of the raw graywater.
Total removal efficiencies averaged approximately 90% or greater in all seasons (Figure 5-18). Removal efficiencies
were greatest during the fall, spring, and summer seasons and lowest during winter months. As with other
carbonaceous compounds, surfactant degradation heavily relies on temperature dependent biological kinetics, which
was reduced during the winter season.
44
-------
I 1 :
GO
< T. -
j J :
^
CO 1
-
;t
.
1
i
1
w
GO
PH
Fall
§
1
w
PH
GO
1
c
]
s
1
w
GO
PH
Winter
L
f
i
1
w
PH
GO
^
J
s
e
w
GO
PH
Spring
^
w
PH
GO
s
<,
*b
1
w
GO
PH
>umme
s
w
PH
GO
r
_
, j
0 «
§ § s
3 3 3
rt 'H-H (H-H
» i W W
OO PL,
^ ^
Overall
n = 2 (fall), 3 (winter and spring) and 4 (summer)
Figure 5-17. Plotted box plots for anionic surfactants as LAS.
100
1FWS Effluent n Total Effluent
0
Fall Winter
Figure 5-18. Percent anionic surfactant removal efficiencies.
Spring
Summer
45
-------
Pathogen Indicators
Concentrations of E. coll are presented for every sampling event (Figure 5-19). Included in the plot are the single
sample maximum and 30-d geometric mean regulations for primary contact recreational waters (EPA, 1986).
E. coli concentrations in the FWS and SF effluents never exceeded the primary contact maximum single-sample limit,
except for two sampling periods in the winter. Note that primary contact regulations limit the 30-d sample mean,
which by regulation requires at least five samples. Due to budget restrictions, less than five samples were collected
monthly; therefore, as a conservative estimate, measured concentrations were also evaluated against the 30-d monthly
geometric mean limit. Aside from winter measurements, only during March, 2009 were FWS effluent concentrations
out of compliance with this limit. Non-winter SF effluents were always within geometric mean limits. EPA
recommended reclaimed water regulations limit fecal coliform concentrations to non-detection on average. As such,
the effluent from the graywater wetland would be out of compliance of these regulations nearly all year. Likewise, the
effluent failed to meet the very strict microbial regulations developed by several states for reclaimed water.
Removal efficiencies of E. coli through the wetland were computed via concentration reductions (instead of using
mass loading), and ranged from approximately 2.2 orders of magnitude in the fall to 1.0 order in the winter (Figure
5-20), with the FWS accounting for the majority of removal. Treatment efficiencies were evaluated by concentration
change as is convention with microbials. Decreased removal rates in the winter likely resulted in the higher E. coli
effluent concentrations observed during that time. Other wetland treatment studies have noted similar inverse
relationships between effluent pathogen indicator concentrations and effluent temperatures (Winward et al., 2008b).
* Inrlii ent
-D-FWSEffluent
OSF Effluent
0
Sep-08 Oct-08Nov-08 Dec-OS Jaii-09 Feb-09 Mar-09 Apr-09May-09 Jun-09 Jul-09 Aug-09
Figure 5-19. Single sample Escherichia coli log concentrations.
46
-------
]FWS Effluent
2.5
] Total Effluent MeanTemperature
Fall
Winter
Spring
Summer
Figure 5-20. Escherichia coli mean removals by log concentrations.
Water Quality Statistical Analysis
Significant differences of the overall data (i.e., all seasons combined), summarized in Table 5-6, were computed using
ANOVA single factor test (a=0.05) with each site tested against each the influent and each bed. Significance in Table
5-6 is shown through the use of letters, i.e., when two sites showed significant difference the letter is the same (e.g.,
A) and when there was no significant difference the letters are different (e.g., A, B, C). Results show that temperature,
SC, TDS and E. coli had no significant change through the wetland. Of note is that E. coli concentrations decreased
substantially through the wetland although the change was not statistically significant. BOD5, TOC and TN were
significantly reduced (p < 0.05) between each of the tested points while for other parameters (DO, turbidity, NH3-N,
TP, PO43", Cl", SO42", anionic surfactant, and TVS), a significant reduction was observed either between the influent
and the FWS effluent or the influent and the SF effluent, but not between the FWS effluent and the SF effluent (p <
0.05). This analysis indicates overall performance of the wetland system.
47
-------
Table 5-6. Water Quality Statistics for All Data Collected
Parameter
Temp
(°C)
DO
(mg/L)
pH
SC
(uS/cm)
Turbidity
(NTU)
BOD5
(mg/L)
TOC
(mg/L)
TN
(mg/L)
Location
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
Mean ± s
13.5 ±5.6
11.9±5.0
10.5 ±5.6
0.19±0.17
2.7 ±2.0
2.2 ±0.5
NA2
NA
NA
229.7 ±50.6
239.9 ±31.7
255.8 ±44.1
31.1 ±18.2
15.2 ±13.0
9.8 ±5.7
86.3 ±40.3
31.7 ±24.0
12.7 ±16.0
43.0 ±17.6
25.9 ±10.3
14.0±11.1
13.5 ±8.7
5.6 ±4.1
n
18
17
17
17
17
17
18
18
18
18
18
18
18
18
18
16
16
14
17
17
16
17
17
Significance
A
B
C
A3
A
B
NA
NA
NA
A
B
C
A3
A
B
A
A
A
A
A
A
A
A
Range
0.4 - 21.9
2.5 - 17.3
1.9 - 20.6
0.0 - 0.6
0.7 - 6.7
0.0 - 3.0
6.0 - 6.8
6.4 - 7.1
6.1 - 7.3
195.0 - 417.0
183.0 - 298.0
183.0 - 334.0
8.1 - 66.7
2.6 - 50.2
1.5 - 19.4
30.6 - 161.6
3.0 - 89.3
1.0 - 54.9
14.2 - 80.4
8.5 - 45.5
3.1 - 46.2
5.7 - 35.0
1.2 - 14.3
48
-------
Parameter
NH3
(mg/L)
TP
(mg/L)
P043-
(mg/L)
cr
(mg/L)
SO42"
(mg/L)
TSS
(mg/L)
TDS
(mg/L)
TVS
(mg/L)
Location
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
Mean ± s
3.0 ±2.6
7.9 ±6.2
2.1 ±3.2
1.7 ±2.0
4.0 ±1.8
1.7 ±1.0
1.3 ±0.7
1.2 ±1.0
0.57 ±0.74
0.4 ±1.2
10.0 ±3.2
9.5 ±3.1
6.8 ±4.7
10.3 ±5.0
9.5 ±4.6
5.0 ±4.6
16.5 ±7.2
12.3 ±7.3
8.0 ±6.2
170.9 ±51. 5
138.7 ±57.8
136.6 ±48.3
138.7 ±50.9
69.4 ±33.6
n
17
18
17
16
18
17
16
18
17
16
18
17
16
18
17
16
17
17
16
11
12
12
11
11
Significance
A
A,B
A
B
A3
A
B
A3
A
B
A
B
A
A
B
A
A
B
A
A
B
C
A3
A
0.0 - 8.2
2.7 - 30.1
0.1 - 11.1
0.1 - 6.0
0.4 - 9.3
2.5 - 3.9
1.9 - 2.9
0.1 - 3.0
0.1 - 2.6
0.1 - 4.9
1.1 - 18.8
0.5 - 15.4
0.1 - 14.1
0.2 - 19.5
0.1 - 16.8
0.1 - 15.6
7.2 - 28.1
2.5 - 30.0
1.1 - 22.2
93.5 - 263.1
10.3 - 218.4
41.9 - 206.3
64.7 - 239.0
10.0 - 115.8
49
-------
Parameter
Anionic
Surfactants
as LAS
(mg/L)
E. coli
(MPN cells
7100 mL)
Location
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Mean ± s
62.8 ±43.5
2.6 ±1.2
0.52 ±0.62
0.28 ±0.27
9.0xl03±2.5xl03
7.3 xlO2 ±23.0xl02
1.2 xlO2 ±2,8xl02
n
11
13
13
13
17
16
16
Significance
B
A,B
A
B
A
B
C
21.3 - 176.0
1.1 - 5.7
0.1 - 2.4
0.0 - 0.9
<10° - 1.0 xlO5
<10° - 9.0 xlO3
<10° - l.lxlO3
Same letters in "Significance" column for a pollutant denote significant differences at P < 0.05 for ANOVA, differing letters
denote no significance.
2 NA= not applicable.
50
-------
Chapter 6 References
American Public Health Association (APHA), American Water Works Association and Water Environment
Federation (1998) Standard Methods for the Examination of Water and Wastewater, 20th ed.; American Public
Health Association: Washington, B.C.
Bergdolt, J., S. Sharvelle and L. Roesner (2011) "Guidance Manual of Graywater from Blackwater for Graywater
Reuse." August, 2011, Water Environment Research Foundation, Stock No. INFR4SG09a, co-published by IWA
publishing.
Casanova, L., V. Little, R. Frye, and C. Gerba. (2001) A Survey of the Microbial Quality of Recycled Household
Graywater. J. Am. Water Res. Assoc., 37 (5), 1313-1319.
City of Los Angeles (1992) Graywater Pilot Project, Final Report. Office of Reclamation at the City of Los Angeles;
Los Angles, CA.
Colorado Department of Public Health and Environment (CDPHE) (2007) Water Quality Control Commission
Regulation 31: Basic Standards and Methodologies for Surface Water. Denver, CO.
CDPHE (2008) Water Quality Control Commission Regulation 84: Reclaimed Water Control Regulation. Denver,
CO.
Cross, J. (1998) Anionic Surfactants: Analytical Chemistry, 2nd ed., rev. and expanded. Surfactant Science Series,
Vol. 73.
Dallas, S. and G. Ho (2005) Subsurface Flow Reedbeds Using Alternative Media for the Treatment of Domestic
Greywater in Monteverde, Costa Rica, Central America. Water Sci. Technol., 51 (10), 119-128.
Dixon , A.; Butler, D.; Fewkes, A.; Robinson, M. (1999) Measurement and Modeling of Quality Changes in Stored
Untreated Grey Water. Urban Water, 1, 293-306.
EPA (1986) Quality Criteria for Water. Report EPA/440/5-86-001, EPA: Washington, DC.
EPA (1993) Subsurface Flow Constructed Wetlands for Wastewater Treatment: A Technology Assessment. Report
EPA 832-R-93-008, EPA: Washington, DC.
EPA (2000a) Constructed Wetlands Treatment of Municipal Wastewaters. Report EPA/625/R-99/010. EPA:
Cincinnati, OH.
EPA (2000b) A Handbook of Constructed Wetlands: A Guide to Creating Wetlands for Agricultural Wastewater,
Domestic Wastewater, Coal Mine Drainage and Stormwater in the Mid-Atlantic Region, Volume 1, General
Considerations. (www.epa.gov/owow/wetlands/pdf/hand.pdf)
EPA (2000c) Wastewater Technology Fact Sheet, Wetlands: Subsurface Flow. Report EPA/832-F-00-023, EPA:
Washington, DC.
EPA (2004) Guidelines for Water Reuse. Report EPA/625/R-04/108, EPA: Washington, DC.
Eriksson, E., K.Auffarth, M. Henze, and A. Ledin (2002) Characteristics of Grey Wastewater. Urban Water, 4, 85-
104.
51
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Florida Cooperative Extension Service (FCES) (2004). Irrigation and Household Water Test and Interpretation.
Institute of Food and Agricultural Sciences, University of Florida Gainesville, FL.
Friedler, E. (2004) Quality of Individual Domestic Greywater Streams and Its Implication for On-site Treatment and
Reuse Possibilities. Environ. Technol., 25 (9), 997-1008.
Friedler, E.,R. Kovalio, and A. Ben-Zvi (2006) Comparative Study of the Microbial Quality of Greywater Treated by
Three On-site Treatment Systems. Environ. Technol., 27 (6), 653-663.
Gross, A., D. Kaplan, and K. Baker (2007a) Removal of Chemical and Microbiological Contaminants from Domestic
Greywater using a Recycled Vertical Flow Bioreactor (RVFB). Ecol. Eng., 31, 107-114.
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Novel Method of Recycling Greywater for Irrigation in Small Communities and Households. Chemosphere, 66 (5),
916-923.
Hammer, D. (1989) Constructed Wetlands for Wastewater Treatment: Municipal, Industrial and Agricultural; Lewis
Publishers: Chelsea, Michigan
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Karpiscak, M., G. France, K. DeCook, R. Brittain, K. Foster and S. Hopf (2001) Casa del Agua: Water Conservation
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Graywater from Various Household Sources, Water Research., 25, 37-42.
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1870.
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197.
52
-------
Appendix A Data
Precipitation Record
The precipitation data as monitored by a Colorado Agricultural Meteorological Network (CoAgMet) weather station
located approximately 650 m from the graywater wetland is presented in Figure-1.
Nov & Feb &
Sep Oct Dec JanMar Apr May Jun
Jul
Aus
10 -
S
s
£
Figure-1. Precipitation record during the sampling period.
Flow Data
The flow data are presented in Table-1. The shaded rows in Table 1 represent sampling events.
Table-1. Flow Rates, Ice Thicknesses and Volumes
Date
9/2/08
9/3/08
9/4/08
9/5/08
9/6/08
9/7/08
9/8/08
9/9/08
9/10/08
Flow (L/d)
Influent
295
360
371
371
314
314
314
386
416
FWS effluent
0
212
269
269
235
235
235
333
322
SW effluent
91
148
235
235
212
212
212
322
280
Ice Thickness
(mm)
FWS
0
0
0
0
0
0
0
0
0
SF
0
0
0
0
0
0
0
0
0
Volume (L)
FWS
2010
2010
2010
2010
2010
2010
2010
2010
2010
SF
2610
2610
2610
2610
2610
2610
2610
2610
2610
-------
Date
9/11/08
9/12/08
9/13/08
9/14/08
9/15/08
9/16/08
9/17/08
9/18/08
9/19/08
9/20/08
9/21/08
9/22/08
9/23/08
9/24/08
9/25/08
9/26/08
9/27/08
9/28/08
9/29/08
9/30/08
10/1/08
10/2/08
10/3/08
10/4/08
10/5/08
10/6/08
10/7/08
10/8/08
10/9/08
10/10/08
10/11/08
10/12/08
10/13/08
10/14/08
10/15/08
10/16/08
10/17/08
10/18/08
10/19/08
10/20/08
10/21/08
10/22/08
10/23/08
10/24/08
10/25/08
10/26/08
Flow (L/d)
Influent
356
363
341
341
341
344
344
344
344
333
333
333
371
371
356
337
337
337
337
401
401
375
326
326
326
326
379
379
379
284
284
284
284
284
284
288
299
299
299
299
382
344
344
299
299
299
FWS effluent
276
939
269
269
269
295
295
295
295
231
231
231
238
238
223
208
208
208
208
269
269
265
254
254
254
254
284
284
284
284
284
284
284
284
284
216
212
212
212
212
310
310
310
322
322
322
SW effluent
257
867
284
284
284
284
284
284
284
174
174
174
185
185
155
167
167
167
167
212
212
204
220
220
220
220
310
310
310
310
310
310
310
310
310
193
178
178
178
178
318
291
291
231
231
231
Ice Thickness
(mm)
FWS
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
SF
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Volume (L)
FWS
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
SF
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
-------
Date
10/27/08
10/28/08
10/29/08
10/30/08
10/31/08
11/1/08
1 1/2/08
1 1/3/08
1 1/4/08
1 1/5/08
1 1/6/08
1 1/7/08
1 1/8/08
1 1/9/08
11/10/08
11/11/08
11/12/08
11/13/08
11/14/08
11/15/08
11/16/08
11/17/08
11/18/08
11/19/08
1 1/20/08
11/21/08
1 1/22/08
1 1/23/08
1 1/24/08
1 1/25/08
1 1/26/08
1 1/27/08
1 1/28/08
1 1/29/08
11/30/08
12/1/08
12/2/08
12/3/08
12/4/08
12/5/08
12/6/08
12/7/08
12/8/08
12/9/08
12/10/08
12/11/08
Flow (L/d)
Influent
299
344
344
284
284
314
314
314
352
352
352
352
333
333
333
333
341
341
367
367
367
367
360
360
356
356
356
356
356
276
276
288
288
288
288
288
288
356
356
371
371
371
371
382
382
360
FWS effluent
322
322
322
265
265
291
291
291
307
307
307
307
344
344
344
344
341
341
322
322
322
322
344
344
326
326
326
326
326
246
246
254
254
254
254
254
254
352
352
405
405
405
405
303
303
356
SW effluent
231
318
318
250
250
265
265
265
295
295
295
295
333
333
333
333
326
326
299
299
299
299
326
326
310
310
310
310
310
235
235
246
246
246
246
246
246
326
326
409
409
409
409
307
307
352
Ice Thickness
(mm)
FWS
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
13
13
13
13
13
13
0
0
0
0
0
0
19
19
25
25
SF
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Volume (L)
FWS
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
1896
1896
1896
1896
1896
1896
2010
2010
2010
2010
2010
2010
1843
1843
1790
1790
SF
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
-------
Date
12/12/08
12/13/08
12/14/08
12/15/08
12/16/08
12/17/08
12/18/08
12/19/08
12/20/08
12/21/08
12/22/08
12/23/08
12/24/08
12/25/08
12/26/08
12/27/08
12/28/08
12/29/08
12/30/08
12/31/08
1/1/09
1/2/09
1/3/09
1/4/09
1/5/09
1/6/09
1/7/09
1/8/09
1/9/09
1/10/09
1/11/09
1/12/09
1/13/09
1/14/09
1/15/09
1/16/09
1/17/09
1/18/09
1/19/09
1/20/09
1/21/09
1/22/09
1/23/09
1/24/09
1/25/09
1/26/09
Flow (L/d)
Influent
159
159
159
148
148
151
151
151
151
151
151
151
151
151
151
151
151
151
151
151
151
151
151
151
151
151
174
167
140
140
140
140
140
148
148
148
148
148
155
155
155
155
155
155
155
155
FWS effluent
151
151
151
53
53
132
132
132
132
132
132
132
132
132
132
132
132
132
132
132
132
117
117
117
117
117
117
117
117
117
117
117
117
125
125
125
125
125
136
136
136
136
136
91
91
91
SW effluent
170
170
170
42
42
95
95
95
95
95
95
95
95
95
95
95
95
95
95
95
95
121
121
121
121
121
110
110
110
110
110
110
110
136
136
136
136
136
121
121
121
121
121
79
79
79
Ice Thickness
(mm)
FWS
25
25
38
38
89
89
89
89
89
89
89
89
89
89
89
89
89
89
89
89
171
171
171
171
171
171
171
152
152
152
152
152
127
127
127
127
127
127
127
127
127
127
89
89
89
89
SF
0
0
0
0
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
38
38
38
38
38
38
38
13
13
13
13
13
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Volume (L)
FWS
1790
1790
1684
1684
1294
1294
1294
1294
1294
1294
1294
1294
1294
1294
1294
1294
1294
1294
1294
1294
765
765
765
765
765
765
765
874
874
874
874
874
1033
1033
1033
1033
1033
1033
1033
1033
1033
1033
1294
1294
1294
1294
SF
2610
2610
2610
2610
2468
2468
2468
2468
2468
2468
2468
2468
2468
2468
2468
2468
2468
2468
2468
2468
2396
2396
2396
2396
2396
2396
2396
2536
2536
2536
2536
2536
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
-------
Date
1/27/09
1/28/09
1/29/09
1/30/09
1/31/09
2/1/09
2/2/09
2/3/09
2/4/09
2/5/09
2/6/09
2/7/09
2/8/09
2/9/09
2/10/09
2/11/09
2/12/09
2/13/09
2/14/09
2/15/09
2/16/09
2/17/09
2/18/09
2/19/09
2/20/09
2/21/09
2/22/09
2/23/09
2/24/09
2/25/09
2/26/09
2/27/09
2/28/09
3/1/09
3/2/09
3/3/09
3/4/09
3/5/09
3/6/09
3/7/09
3/8/09
3/9/09
3/10/09
3/11/09
3/12/09
3/13/09
Flow (L/d)
Influent
291
291
291
375
375
375
375
371
371
371
375
375
375
375
375
375
375
371
371
371
371
360
360
360
360
363
363
363
363
170
170
170
390
390
390
322
322
322
322
375
375
375
375
375
375
375
FWS effluent
201
201
201
314
314
314
314
333
333
333
367
367
367
367
326
326
326
333
333
333
333
326
326
326
326
303
303
303
303
174
174
174
174
174
174
265
265
265
265
337
337
337
337
326
326
326
SW effluent
189
189
189
344
344
344
344
326
326
326
360
360
360
360
322
322
322
322
322
322
322
314
314
314
314
291
291
291
291
159
159
159
254
254
254
250
250
250
250
322
322
322
322
250
250
250
Ice Thickness
(mm)
FWS
89
89
121
121
121
121
121
121
121
76
76
76
76
70
70
70
64
64
64
64
44
44
44
44
25
25
25
25
13
13
13
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
SF
0
0
25
25
25
25
25
25
25
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Volume (L)
FWS
1294
1294
1075
1075
1075
1075
1075
1075
1075
1389
1389
1389
1389
1438
1438
1438
1484
1484
1484
1484
1635
1635
1635
1635
1790
1790
1790
1790
1896
1896
1896
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
SF
2610
2610
2468
2468
2468
2468
2468
2468
2468
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
-------
Date
3/14/09
3/15/09
3/16/09
3/17/09
3/18/09
3/19/09
3/20/09
3/21/09
3/22/09
3/23/09
3/24/09
3/25/09
3/26/09
3/27/09
3/28/09
3/29/09
3/30/09
3/31/09
4/1/09
4/2/09
4/3/09
4/4/09
4/5/09
4/6/09
4/7/09
4/8/09
4/9/09
4/10/09
4/11/09
4/12/09
4/13/09
4/14/09
4/15/09
4/16/09
4/17/09
4/18/09
4/19/09
4/20/09
4/21/09
4/22/09
4/23/09
4/24/09
4/25/09
4/26/09
4/27/09
4/28/09
Flow (L/d)
Influent
375
375
375
375
375
375
375
375
375
386
386
386
386
386
363
363
443
443
386
386
386
386
386
379
379
379
379
379
333
333
333
435
435
435
394
394
394
394
394
367
367
367
367
367
367
367
FWS effluent
326
326
326
326
326
246
246
246
246
322
322
322
322
322
568
568
333
333
450
450
450
450
450
413
413
413
413
413
238
238
238
178
178
178
1075
1075
1075
1075
1075
303
303
303
303
303
303
303
SW effluent
242
242
242
242
242
246
246
246
246
367
367
367
367
367
776
776
435
435
394
394
394
394
394
553
553
553
553
553
235
235
235
174
174
174
1283
1283
1283
1283
1283
307
307
307
307
307
307
307
Ice Thickness
(mm)
FWS
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
6
6
6
6
6
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
SF
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Volume (L)
FWS
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
1953
1953
1953
1953
1953
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
SF
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
-------
Date
4/29/09
4/30/09
5/1/09
5/2/09
5/3/09
5/4/09
5/5/09
5/6/09
5/7/09
5/8/09
5/9/09
5/10/09
5/11/09
5/12/09
5/13/09
5/14/09
5/15/09
5/16/09
5/17/09
5/18/09
5/19/09
5/20/09
5/21/09
5/22/09
5/23/09
5/24/09
5/25/09
5/26/09
5/27/09
5/28/09
5/29/09
5/30/09
5/31/09
6/1/09
6/2/09
6/3/09
6/4/09
6/5/09
6/6/09
6/7/09
6/8/09
6/9/09
6/10/09
6/11/09
6/12/09
6/13/09
Flow (L/d)
Influent
352
352
352
26
26
26
284
284
284
284
227
227
227
227
227
201
201
201
201
201
132
106
106
114
114
114
114
114
53
53
53
53
53
117
117
117
140
140
140
140
140
140
189
189
189
189
FWS effluent
291
291
291
110
110
110
197
197
197
197
246
246
246
246
246
117
117
117
117
117
19
4
4
246
246
246
246
246
30
30
30
30
30
34
34
34
587
587
587
587
587
587
87
87
87
87
SW effluent
269
269
269
167
167
167
159
159
159
159
257
257
257
257
257
68
68
68
68
68
0
0
0
269
269
269
269
269
11
11
11
11
11
79
79
79
632
632
632
632
632
632
79
79
79
79
Ice Thickness
(mm)
FWS
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
SF
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Volume (L)
FWS
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
SF
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
-------
Date
6/14/09
6/15/09
6/16/09
6/17/09
6/18/09
6/19/09
6/20/09
6/21/09
6/22/09
6/23/09
6/24/09
6/25/09
6/26/09
6/27/09
6/28/09
6/29/09
6/30/09
7/1/09
7/2/09
7/3/09
7/4/09
7/5/09
7/6/09
7/7/09
7/8/09
7/9/09
7/10/09
7/11/09
7/12/09
7/13/09
7/14/09
7/15/09
7/16/09
7/17/09
7/18/09
7/19/09
7/20/09
7/21/09
7/22/09
7/23/09
7/24/09
7/25/09
7/26/09
7/27/09
7/28/09
7/29/09
Flow (L/d)
Influent
189
189
102
102
484
484
484
484
484
534
534
534
534
360
360
360
360
522
522
522
148
148
148
231
231
231
231
117
117
117
269
269
522
522
522
431
431
155
155
155
155
155
155
155
155
235
FWS effluent
87
87
344
344
238
238
238
238
238
942
942
942
942
310
310
310
310
280
280
280
363
363
363
121
121
121
121
4
4
4
4
4
0
0
0
0
0
409
409
409
409
409
409
409
409
250
SW effluent
79
79
132
132
132
132
132
132
132
132
132
132
132
273
273
273
273
4
4
4
4
4
4
8
8
8
8
8
8
8
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Ice Thickness
(mm)
FWS
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
SF
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Volume (L)
FWS
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
2006
SF
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
2610
-------
Date
7/30/09
7/31/09
8/1/09
8/2/09
8/3/09
8/4/09
Flow (L/d)
Influent
235
235
276
276
276
367
FWS effluent
250
250
57
57
57
91
SW effluent
4
4
4
4
4
4
Ice Thickness
(mm)
FWS
0
0
0
0
0
0
SF
0
0
0
0
0
0
Volume (L)
FWS
2006
2006
2006
2006
2006
2006
SF
2610
2610
2610
2610
2610
2610
Water Quality Data
The following tables contain the water quality data collected during the one-year monitoring period. The tables are
broken down into different seasons, fall (Table-2), winter and spring (Table-3) and summer (Table~4).
Table-2. Fall Graywater Quality Data
Season
Date
DO (mg/L)
Temp (°C)
pH
S
C (uS/cm)
BOD5
(mg/L)
TOC (mg/L)
DOC (mg/L)
TN (mg/L)
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
Fall
9/19/2008
0.2
17.6
6.5
6.9
6.8
218.0
235.0
256.0
76.7
46.5
26.5
13.0
29.2
8.1
Fall
9/24/2008
0.1
3.0
1.4
13.7
15.1
16.3
6.1
6.7
6.5
197.4
240.0
283.0
79.3
19.3
33.1
17.5
10.6
22.3
13.5
6.0
Fall
10/1/2008
0.1
1.8
2.3
13.1
14.1
15.6
6.0
6.7
6.4
201.2
249.7
294.2
20.0
4.5
47.9
23.0
6.5
8.0
Fall
10/7/2008
0.1
4.4
3.0
10.8
12.9
13.5
6.2
6.7
6.5
208.0
266.0
299.0
30.8
28.0
8.4
8.2
Fall
10/23/2008
0.2
5.5
2.8
5.9
8.7
8.6
6.2
6.8
6.3
223.0
264.0
287.0
53.8
18.9
2.4
32.1
23.2
6.6
9.1
Fall
10/29/2008
0.1
3.2
2.8
12.0
9.3
9.8
6.2
6.6
6.3
219.0
255.0
288.0
88.1
28.3
1.0
41.2
21.1
3.1
9.9
Fall
11/19/2008
0.0
1.3
2.0
14.8
7.8
10.3
6.6
6.6
6.4
213.0
267.0
271.0
109.5
37.4
4.7
52.1
24.9
11.6
33.2
18.1
9.8
13.2
-------
Season
Date
NH3,
mg/L
NO3"
(mg/L)
DTN (mg/L)
TP (mg/L)
P043- (mg/L)
E1. co//'
(MPN cells
7100 mL)
Anionic
Surfactants
as LAS
(mg/L)
cr
(mg/L)
SO42"
(mg/L)
Turbidity,
(NTU)
TS (mg/L)
TS S (mg/L)
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
Fall
9/19/2008
6.1
2.5
4.9
BDL1
6.7
2.4
0.9
10.9
14.1
28.3
25.1
13.4
24.8
Fall
9/24/2008
2.8
1.6
3.1
0.7
BDL
BDL
5.9
2.3
2.3
0.6
0.7
0.1
884.0
8.9
8.6
11.4
16.8
10.6
6.0
7.9
16.0
Fall
10/1/2008
3.0
1.1
5.2
0.1
0.4
BDL
BDL
0.1
2.8
1.0
1.9
1.1
0.1
0.1
1658.0
41.0
38.7
9.7
8.9
6.9
11.0
11.8
3.2
8.1
5.6
7.7
12.3
Fall
10/7/2008
2.8
0.8
4.5
0.2
0.2
BDL
BDL
0.2
3.1
1.6
1.5
1.4
0.1
BDL
5610.0
12.5
8.2
8.9
9.1
8.1
12.4
11.0
6.2
11.2
7.9
7.3
10.4
Fall
10/23/2008
4.6
0.7
6.4
1.3
0.2
BDL
0.1
0.3
3.3
1.6
0.7
1.7
0.1
BDL
1300.0
9.1
6.0
10.1
10.3
8.3
16.3
14.2
15.6
17.0
9.2
2.8
8.3
Fall
10/29/2008
4.6
0.5
6.5
1.7
0.2
BDL
0.1
0.5
3.3
1.4
0.5
1.4
0.1
0.1
2103.0
3.0
2.0
1.1
0.2
0.0
8.9
9.9
8.5
10.8
11.4
12.0
22.4
9.2
1.5
12.9
Fall
11/19/2008
9.4
1.7
8.3
6.2
0.9
BDL
0.2
0.1
11.0
7.9
1.5
3.8
1.8
0.7
1.9
0.5
BDL
80.0
8.0
4.0
2.3
0.2
0.1
9.5
11.0
11.2
5.3
10.6
7.6
40.7
12.5
2.3
161.5
91.5
99.5
10
-------
Season
Date
TDSo
(mg/L)
TVS (mg/L)
VSS (mg/L)
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Influent
FWS
Effluent
SF Effluent
Fall
9/19/2008
Fall
9/24/2008
5.3
Fall
10/1/2008
13.2
5.8
Fall
10/7/2008
20.4
8.0
Fall
10/23/2008
14.1
1.7
Fall
10/29/2008
8.7
1.1
Fall
11/19/2008
8.2
3.2
91.5
99.5
118.0
69.5
60.5
6.2
2.0
BDL - below detection limit.
Table-3. Winter and Spring Graywater Quality Data
Season
Date
DO
(mg/L)
Tern (°C)
pH
SC
(uS/cm)
BOD5
(mg/L)
TOC
(mg/L)
DOC
(mg/L)
TN
(mg/L)
NH3
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
Winter
12/10/2008
0.1
1.1
2.4
14.8
7.8
10.3
6.7
6.7
6.7
260.0
298.0
308.0
118.6
70.6
54.8
36.0
14.4
35.9
24.5
12.8
19.8
12.7
5.2
13.9
Winter
1/26/2009
0.1
1.1
2.2
11.3
2.5
1.9
6.8
6.4
6.5
256.0
286.0
334.0
109.3
62.3
54.9
61.9
39.4
33.0
37.6
31.4
26.5
16.7
8.6
8.2
11.0
Winter
2/24/2009
0.1
1.2
2.1
21.9
2.8
3.5
6.6
6.4
6.7
220.0
241.0
261.0
150.3
89.3
36.3
54.4
29.8
12.5
30.3
17.8
5.71
12.3
11.1
7.9
7.0
Spring
3/31/2009
0.3
6.7
2.7
0.4
4.7
4.5
6.4
6.7
6.6
205.0
210.0
219.0
120.4
30.3
16.2
80.4
45.5
46.2
36.2
24.5
20.1
10.8
2.0
4.8
5.8
Spring
4/16/2009
0.1
4.3
1.8
8.1
7.2
9.0
6.3
6.8
6.6
195.0
217.0
271.0
92.5
29.3
26.4
44.6
29.8
21.8
26.5
20.2
19.1
5.7
3.5
5.2
7.9
Spring
4/28/2009
0.2
6.3
2.7
6.5
7.4
8.5
6.2
6.7
6.5
208.0
183.0
183.0
161.6
10.1
4.3
61.4
18.4
9.81
33.7
17.8
8.3
10.8
1.9
2.5
2.7
Spring
5/18/2009
0.6
1.7
2.8
16
11.5
14
6.2
6.5
7.3
237.0
263.0
200.0
39.9
27.4
3.0
22.3
40.8
10.8
14.8
26.9
8.4
35
14.3
5.2
8.5
11
-------
Season
Date
(mg/L)
NO3" (mg/L)
DTN
(mg/L)
TP
(mg/L)
P043- (mg/L)
E1. co//'
(MPN cells
/100 mL)
Anionic
Surfactants as
LAS, (mg/L)
cr
(mg/L)
so42-
(mg/L)
Turbidity
(NTU)
TS
(mg/L)
TSS
(mg/L)
TDS
(mg/L)
TVS
(mg/L)
vss
(mg/L)
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Winter
12/10/2008
11.1
4.0
BDL
BDL
0.2
17.4
11.2
5.2
4.7
3.1
0.8
3.0
1.6
BDL
7009.0
2420.0
1054.0
3.2
0.8
0.3
9.4
11.9
14.1
7.2
9.2
4.1
58.2
38.1
10.1
180.0
151.7
154.2
28.1
9.4
5.4
151.9
142.3
148.8
130.0
115.8
73.3
24.4
7.2
3.4
Winter
1/26/2009
5.4
6.0
BDL
0.2
0.2
15.1
7.8
7.9
6.1
3.9
2.9
2.7
0.9
BDL
115.0
28.0
132.0
3.1
0.9
0.8
10.3
10.7
12.2
6.8
9.9
10.1
51.3
32.6
19.3
110.0
138.3
201.7
16.5
7.7
8.5
93.5
130.6
193.1
94.4
95.6
91.1
13.3
6.4
5.8
Winter
2/24/2009
6.2
5.1
BDL
BDL
0.2
10.7
9.7
7.3
3.7
3.2
2.6
2.2
1.1
BDL
102035.0
8975.0
488.4
5.7
2.4
0.9
10.9
10.7
10.5
8.3
10.5
3.9
66.7
50.2
19.4
164.7
112.0
48.7
28.1
11.1
6.8
136.5
100.9
41.9
144.7
84.0
32.7
21.7
7.5
3.9
Spring
3/31/2009
0.2
2.3
BDL
BDL
BDL
10.2
3.8
5.1
3.5
2.9
1.3
BDL
BDL
BDL
29546.7
133.3
67.7
1.9
0.5
0.3
>10
>10
>10
6.1
7.2
4.4
46.5
10.2
9.7
172.0
135.3
135.3
8.5
18.4
5.2
163.5
116.9
130.1
7.5
15.5
4.3
Spring
4/16/2009
0.3
4.3
BDL
BDL
BDL
4.0
1.6
4.8
2.2
1.8
1.5
BDL
BDL
BDL
143.0
5.0
1.0
2.7
0.6
0.4
>10
>10
>10
6.1
3.8
0.8
40.8
7.4
4.6
250.0
228.0
200.0
10.2
22.7
2.8
239.8
205.3
197.2
122.0
101.0
72.0
8.4
19.9
2.4
Spring
4/28/2009
0.3
1.6
BDL
BDL
BDL
9.4
1.8
2.3
3.9
0.7
1.3
BDL
BDL
BDL
10.3
<1
<1
2.3
0.1
0.1
>10
>10
3.3
10.2
0.1
0.9
54.6
2.6
3.4
288.0
16.0
209.3
24.9
5.7
3.1
263.1
10.3
206.3
239.0
10.0
176.0
23.1
2.9
1.9
Spring
5/18/2009
0.19
0.44
BDL
BDL
BDL
32.3
7.0
4.0
3.4
2.0
1.5
BDL
BDL
BDL
<1
<1
19
1.2
0.14
0.08
>10
>10
>10
18.9
15.4
10.0
148.7
228.0
232.0
7.2
30
12.7
141.5
198.0
122.7
64.7
94.0
40.7
6.7
23.5
5.7
BDL - below detection limit.
12
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Table-4. Summer Graywater Quality Data
Season
Date
DO
(mg/L)
Temp (°C)
pH
S
C (uS/cm)
BOD5
(mg/L)
TOC
(mg/L)
DOC
(mg/L)
TN, (mg/L)
NH3
mg/L
NO3"
(mg/L)
DTN
(mg/L)
TP (mg/L)
(mg/L)
E. coli
(MPN cells/100
mL
Anionic
Surfactants as
LAS (mg/L)
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Summer
6/30/2009
1.1
2.1
20.7
16.1
17.8
6.2
6.5
7.3
203.0
226.0
223.0
31.2
40.7
12.9
14.5
12.5
12.7
1.7
10.3
4.4
4.1
0.61
0.16
<0.2
0.2
<0.2
9.0
2.6
0.76
2.2
1.5
1.5
0.24
<0.2
0.2
44.3
12.7
14.7
2.0
0.35
0.18
Summer
7/8/2009
0.08
0.9
1.3
17.5
16.5
18.5
6.7
6.7
6.3
247.0
205.0
204.0
46.8
11.3
2.2
4.4
0.13
0.13
O.2
0.2
O.2
6.3
0.95
0.60
0.2
0.41
4.9
290.9
6
4
3.3
0.23
0.12
Summer
7/20/2009
0.30
1.6
1.5
19.1
17.3
20.6
6.8
6.7
6.5
417.0
220.0
221.0
71.6
8.6
6.3
38.2
14.9
8.8
22.0
10.1
5.6
34.3
2.7
1.8
30.1
1.2
0.47
O.2
0.2
1.3
32.2
2.4
1.4
9.3
0.85
0.65
2.6
2.6
0.2
1299.7
6
<1
3.7
0.26
0.26
Summer
8/4/2009
0.53
0.71
1.8
18.2
17.1
18.8
6.8
7.1
6.9
207.7
192.9
202.5
30.6
3.0
2.5
14.2
8.5
6.2
10.8
8.8
5.7
10.7
1.2
0.8
7.2
0.40
0.84
O.2
0.2
O.2
10.1
1.2
0.7
5.7
0.76
0.53
0.2
1.5
0.2
290.9
<1
33
1.8
0.20
0.20
13
-------
Season
Date
Cr (mg/L)
so42-
mg/L
Turbidity (NTU)
TS
(mg/L)
TSS
(mg/L)
TDS
(mg/L)
TVS
(mg/L)
vss
(mg/L)
Influent
FWS Effluent
SF Effluent
Influent
FWS
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Influent
FWS Effluent
SF Effluent
Summer
6/30/2009
>10
4.5
0.20
0.24
<0.2
0.2
14.5
15.9
18.5
209.3
194.0
130.7
10.4
14.9
22.2
198.9
179.1
108.5
69.3
51.0
34.0
9.1
11.3
10.4
Summer
7/8/2009
9.9
0.51
0.2
17.3
10.3
2.1
21.3
8.0
13.9
236.0
232.0
112.7
22.0
13.6
11.7
214.0
218.4
100.9
93.3
75.3
28.7
19.1
8.4
6.1
Summer
7/20/2009
>10
>10
1.0
6.7
114.1
8.5
23.8
4.7
13.6
166.0
132.0
144.0
20.3
3.7
20.3
145.7
128.3
123.7
67.3
25.0
21.3
18.4
1.9
6.8
Summer
8/4/2009
1.1
>10
0.20
19.5
12.9
0.2
24.4
12.8
10.4
150.7
145.0
176.0
19.3
2.5
9.0
131.3
142.5
167.1
72.0
42.0
60.7
16.3
0.80
3.6
14
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