a pilot scale study of low dissolved oxygen nutrient
TRANSCRIPT
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A Pilot Scale Study of Low Dissolved Oxygen Nutrient Removal
Supplemented with Ammonia-Based Aeration Controls
Prepared by:
Evan D. Chambers
A thesis submitted in partial fulfillment of the
requirements for the degree of
Master of Science
(Environmental Engineering)
at the
UNIVERSITY OF WISCONSIN-MADISON
2018
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TABLE OF CONTENTS
LIST OF FREQUENTLY USED ABBREVIATIONS 4
LIST OF FIGURES 6
LIST OF TABLES 9
LIST OF SUPPLEMENTARY FIGURES & TABLES 10
ACKNOWLEDGEMENTS 11
ABSTRACT 1
CHAPTER 1: INTRODUCTION 2
1.1 Nutrient Removal from Anthropogenic Liquid Waste Streams 2
1.2 Point Source Discharges in Wisconsin 4
1.3 Energy Usage for Wastewater Treatment 6
1.4 Conventional Process Control Schemes 7
1.5 Temperature Effects on Wastewater Treatment 8
1.6 General Objectives of This Thesis 9
CHAPTER 2: MATERIALS AND METHODS 11
2.1 Pilot Plant Process Configurations 11
2.2 Pilot Plant Operations 13
2.3 Pilot Plant Process Control 15
2.4 Pilot Plant Maintenance & Sampling 18
CHAPTER 3: RESULTS AND DISCUSSION 22
3.1 Influent Conditions 22
3.2 Temperature Influences on Pilot Performance 25
3.3 Ammonia Tracking 27
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3.4 Ammonia-Based Controls Trending 32
3.5 Effects of Ammonia-Based Aeration Controls – Aeration Capacity 36
3.6 Effects of Ammonia-Based Aeration Controls – Aeration Limitation 44
3.7 Effects of Ammonia-Based Aeration Controls – Exceedance Evaluation 48
3.8 Simultaneous Nitrification and Denitrification 50
3.9 Nutrient Profiles 53
3.10 Clarifier Considerations 60
CHAPTER 4: RECOMMENDATIONS 63
4.1 Sampling Methods 63
4.2 Hydraulic Residence Time 64
4.3 Solids Residence Time 65
4.4 Probe Usage 66
4.5 Intermittent Aeration 67
4.6 Dissolved Oxygen Tracking 69
4.7 Alkalinity Monitoring 70
4.8 Reduction in High Strength Recycle Streams 70
4.9 Monitoring of Process Flows 71
CHAPTER 5: CONCLUSIONS 72
REFERENCES 74
APPENDIX A 1
APPENDIX B 1
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LIST OF FREQUENTLY USED ABBREVIATIONS
AOB Ammonia Oxidizing Bacteria
BNR Biological Nutrient Removal
BOD Biochemical Oxygen Demand
COD Chemical Oxygen Demand
DO Dissolved Oxygen
EBPR Enhanced Biological Phosphorus Removal
HRT Hydraulic Residence Time
MLSS Mixed Liquor Suspended Solids
NOB Nitrite Oxidizing Bacteria
NSWWTP Nine Springs Wastewater Treatment Plant
RAS Return Activated Sludge
SND Simultaneous Nitrification and Denitrification
SRT Solids Residence Time
SVI Sludge Volume Index
TKN Total Kjeldahl Nitrogen
TN Total Nitrogen
TP Total Phosphorus
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TSS Total Suspended Solids
VSS Volatile Suspended Solids
WAS Waste Activated Sludge
WWTP Wastewater Treatment Plant
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LIST OF FIGURES
Figure 2.2.1 UCT pilot configuration schematic and details
Figure 2.2.2 Johannesburg pilot configuration schematic and details
Figure 2.3.1 UCT process control and aeration schematic
Figure 3.1.1 Monthly average influent concentrations and seasonal temperature variation
Figure 3.2.1 Historical summary of temperature fluctuations and nitrification upsets
Figure 3.2.2 Correlation analysis of wastewater temperature and effluent ammonia concentration
Figure 3.2.3 Effluent grab sampling results for NH3 concentration during warm water
operations
Figure 3.3.1 15-minute ammonia data within aerobic mixed liquor for the month of September
2017
Figure 3.3.2 15-minute ammonia data within aerobic mixed liquor for the month of October 2017
Figure 3.3.3 15-minute ammonia data within aerobic mixed liquor for the month of November
2017
Figure 3.3.4 15-minute ammonia data within aerobic mixed liquor for the first 12 days of the
month of December 2017
Figure 3.3.5 Daily variability in ammonia within the mixed liquor for Sunday, October 22nd,
2017.
Figure 3.4.1 Start of ammonia based control strategy with NH3 setpoint of 3 mg/L and high DO
setpoint of 1 mg/L
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Figure 3.4.2 Pilot response to a decreased ammonia setpoint of 1 mg/L while maintaining a high
DO setpoint of 1 mg/L
Figure 3.4.3 Daily average wastewater temperatures during the month of December, 2017
Figure 3.4.4 Daily average NH3 and DO during process upsets in January, 2018
Figure 3.5.1 September 2017 pilot aeration capacity usage per day
Figure 3.5.2 October 2017 pilot aeration capacity usage per day
Figure 3.5.3 November 2017 pilot aeration capacity usage per day
Figure 3.5.4 December 2017 pilot aeration capacity usage per day
Figure 3.5.5 January 2018 pilot aeration capacity usage per day
Figure 3.5.6 February 2018 pilot aeration capacity usage per day
Figure 3.5.7 March 2018 pilot aeration capacity usage per day
Figure 3.6.1 Oxygen deficiency analysis within the pilot aerobic zone
Figure 3.7.1 Effluent ammonia exceedance counts for 2017 operation
Figure 3.7.2 Effluent ammonia exceedance counts for 2018 operation
Figure 3.8.1 SND calculation summary for the pilot operated as UCT
Figure 3.8.2 Effluent NOx and NH3 concentrations for the pilot operated as UCT
Figure 3.9.1 Monthly average nutrient profile sampling results for July, 2017
Figure 3.9.2 Monthly average nutrient profile sampling results for August, 2017
Figure 3.9.3 Monthly average nutrient profile sampling results for September, 2017
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Figure 3.9.4 Monthly average nutrient profile sampling results for October, 2017
Figure 3.9.5 Monthly average nutrient profile sampling results for November, 2017
Figure 3.9.6 Monthly average nutrient profile sampling results for December, 2017
Figure 3.9.7 Monthly average nutrient profile sampling results for January, 2018
Figure 3.9.8 Monthly average nutrient profile sampling results for February, 2018
Figure 3.9.9 Monthly average consumption rates from the anoxic zone to the pilot effluent
Figure 3.10.1 Monthly average SVI trending across low DO operation and ammonia-based
control implementation
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LIST OF TABLES
Table 1.2.1 Permitted effluent limits at NSWWTP for ammonia
Table 2.3.1 Ammonia-based aeration control setpoint changes summary
Table 3.1.1 Monthly average summary for nitrogenous influent conditions from NSWWTP Lab
Table 3.1.2 Monthly average summary for various influent conditions from NSWWTP Lab
Table 3.1.3 Monthly average summary for influent phosphate conditions from University of
Wisconsin-Madison Environmental Engineering Lab
Table 3.4.1 Monthly average wastewater temperature summary
Table 3.6.1 Monthly totals of oxygen deficiency within the pilot aerobic zone
Table 3.10.1 Monthly average SVI summaries for two settling test containers
Table 4.3.1 Historical MLSS concentrations from pilot aerobic tank 2
Table 4.5.1 Summary of fixed airflow meter conditions and recommendations
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LIST OF SUPPLEMENTARY FIGURES & TABLES
Figure S.1 Historical timeline of pilot temperatures and effluent ammonia grab sample results
Table S.1 Monthly average influent concentrations for various constituents in the pilot feed stream
Table S.2 Monthly average SVI (mL/g) calculations for settleability test in 1000 mL plastic
cylinder
Table S.3 Monthly average SVI (mL/g) calculations for settleability test in 1000 mL glass beaker
Table S.4 Monthly average MLSS (mg/L) concentrations collected from aerobic tank 2
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ACKNOWLEDGEMENTS
Pursing this degree as a nontraditional student would have been impossible without the
support and assistance from a number of individuals and groups. I need to first acknowledge the
support and accommodations made from the staff at Town & Country Engineering. Without their
vested interest in me as a young professional this experience could have never occurred. Town &
Country saw the value in my continued education and did everything they could, and then some,
to make the experience a successful and enjoyable one. A very heartfelt thanks goes to them, as I
reflect on the last 18 months of continuing to work for the firm while earning this prestigious
degree.
In addition to the adjustments those made outside of the University, I feel the need to
express my genuine thanks to my advisor, Dr. Daniel Noguera, who was extremely
accommodating throughout this process. Scheduling conflicts and work related obligations made
our relationship feel distant at times, but Dan was always enthusiastic about picking up where we
last left off and making sure to guide me down the right path. His passion for the research within
the field of wastewater treatment is refreshing and encouraging, and something that I will forever
admire. Again, thank you Dan, for all you have done for me to make me a better engineer in this
continuously progressing field.
To Dr. Katherine McMahon and Dr. Greg Harrington, thank you for the work you have
done in the classroom and for serving on my defense committee. You both bring so much to the
table as educators and I truly value the lessons learned and time together through the course of my
time at the University.
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The folks at Madison Metropolitan Sewerage District also deserve the utmost thanks, for
without your desire to continuously improve processes in the wastewater treatment plant the space
and funding for this research would be nonexistent. I am grateful for the opportunity to have
worked at such a great facility with incredible staff. Matt Seib, thank you for your devotion to the
pilots and always being there when I needed information, data, or help. An additional thanks to all
of the lab staff at MMSD, for processing piles of samples for our research.
I must also address the team of students and peers that I was fortunate enough to work
alongside. To the Noguera group, thanks for always offering valuable suggestions and insight into
the research. Your constructive comments and feedback were extremely useful in compiling
everything being presented. A big thanks to Nick Bayer, fellow pilot researcher, for all of the time
and effort you devoted to keeping our reactors alive and ensuring the quality of work was
maintained. Also, thanks to Natalie Keene who turned over her pilot work to us and provided
advice and recommendations whenever troubleshooting occurred. Without her reconstruction of
the pilot and constant devotion to it, none of this research would have been available for me.
Finally, I must reach out to the various undergraduate assistants that helped with maintenance at
the pilot and the lab work. Without your help in day to day operations, this experience would not
have been anywhere close to the same.
Last, but not least, thanks to my family and friends who understood the commitment I made
to myself and this experience and supported me the entire way through. The process was not easy
and your constant reminders and reassurance helped me get to where I am today.
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ABSTRACT
In order to refine a previously acclimated pilot to low dissolved oxygen (DO) conditions for
nutrient removal, ammonia-based aeration control was introduced in an effort to successfully
remove ammonia throughout an entire year. Historical operations of the low DO pilot, operated at
a fixed DO setpoint of 0.5 mg/L, allowed for efficient nutrient removal until water temperatures
decreased with drastic seasonal changes present in at the Nine Springs Wastewater Treatment Plant
in Madison, WI. By implementing ammonia-based aeration controls in the secondary treatment
process, triggered by operator adjustable ammonia setpoints, the pilot was allowed to operate
between high and low DO modes to call for additional oxygen when ammonia loads increased,
and call for less oxygen, as an energy saver, when an ammonia setpoint is achieved. In addition,
data from the ammonia probe was compiled and summarized which provides an enhanced
understanding of the process that was previously not possible to obtain. This shows the daily, and
even hourly, variability that the pilot experiences in response to influent loadings and seasonal
transitions. In comparing the first iteration of ammonia-based controls with the previous years of
fixed DO operation, recommendations and enhancements are provided to optimize the process for
future work. The study provided insight into the various physical configurations to be considered
with the control strategy and also evaluates the side effects, both positive and negative, that come
with implementing ammonia-based controls on a low DO pilot reactor.
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CHAPTER 1: INTRODUCTION
1.1 Nutrient Removal from Anthropogenic Liquid Waste Streams
Wastewater treatment plants (WWTPs) are an engineered system in which spent water from any
number of inputs is directed for removal of various nutrients prior to discharge to wetlands, surface
waters, or groundwater. A number of constituents within typical wastewater are subject to
permitted regulations in which concentrations or loads must be below a threshold prior to discharge
to the environment. These commonly include; biochemical oxygen demand (BOD), total
suspended solids (TSS), ammonia (NH3), and phosphorus. Additional permitted constituents are
applied to industrial facilities, as well as some municipal WWTPs, which can include mercury,
zinc, chromium, iron and other metals, for example15. Specifically in regards to nitrogenous
species, ammonia is toxic to fish and aquatic life and thus is heavily regulated to limit deadly fish
kills and unsafe freshwater ecosystems. Nonetheless, on a global scale, WWTPs contribute a
significant amount of ammonia, nitrite (NO2-) and nitrate (NO3
-) to surface waters through liquid
discharged to the environment. The discharge of total nitrogen from WWTPs includes ammonia,
nitrite, nitrate, and other forms and the makeup is critical to the wellbeing of the receiving stream
or waterbody. Nitrite is seldom discharged in concentrations greater than 1 mg/L (0.3 NO2- - N
mg/L) which results in a concentration typically below 0.1 mg/L (0.03 NO2- - N mg/L) in the
surface water it is discharged to. Because of its toxicity, the successful conversion of ammonia to
nitrate, N2 gas and/or biomass is an important process within the treatment of liquid waste streams1.
Efficient and reliable nutrient removal is becoming increasingly important while both
eutrophication and energy neutrality come to the forefront of WWTP operations and goals19. The
environmental condition termed eutrophication, a scenario in which a waterbody has accumulated
nutrients in excess such that toxic conditions frequently develop, has been a focus for nutrient
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reduction efforts at both point source and non-point source levels. Point source discharge includes
end of pipe sources such as WWTPs, industries, and stormwater conveyance systems. Non-point
source contributions come from agricultural fertilizer runoff, atmospheric deposition, and
biological nitrogen fixation, among others30. The categories of nutrient loadings to surface waters
are generally classified by one of two descriptions. Acute effects are associated with events over
an identifiable period of time in which loadings increase and the DO decreases. Conversely, the
gradual long-term effects are referred to as accumulative effects. Dependent upon the residence
time of the water body or the turnover in the water or sediments, nutrients accumulate over time
which develop water quality concerns16.
In the state of Wisconsin, approximately 58% of the federally recognized impaired waters
are due to nonpoint source pollution, about 75% of which is caused by urban and/or agricultural
runoff. Other nonpoint sources include atmospheric deposition, contaminated sediments, and
physical habitat. Of the federally recognized impaired waters in the state, 16% are sourced from
point sources or a point and nonpoint source blend20. The predominant point source discharger of
nutrients into lakes, rivers, and streams are WWTPs. Although in general nutrient discharge from
WWTPs has long term detrimental effects related to eutrophication, studies show that downstream
of WWTP effluent discharges has an increase in abundance of fish relative to upstream reaches of
the same waterbody, directly related to the increased availability of food concentrated around the
effluent plume which is high in nutrients18. Nonetheless, the end of pipe effluent limits for these
dischargers have become increasingly stringent to reduce nutrient discharge, specifically for
nitrogen (N), phosphorus (P), and carbon. N, P, and carbon are macro-nutrients, essential for all
life, including in aquatic ecosystems. However, when in excess it has been shown that N and P can
accumulate in the sediments which can then be mobilized and released through diffusion when
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redox conditions are favorable17. Thus, even if the soluble nutrients were diminished in the water,
an additional pool has been developed in the underlying sediments due largely in part to
anthropogenic sources. When these elemental nutrients are in excess, algae and bacteria growth
occurs rapidly, and dead zones are developed within the water body. Dead zones, sometimes
referred to as oxygen minimum zones (OMZs), are described as areas within the water column
were DO concentrations are reduced to ecologically unsafe levels22. These dead zones, because of
the algal growth and bacterial respiration, create hypoxic (<3 mg/L DO) and/or anoxic (<0.2 mg/L
DO) conditions in which most aquatic life struggles21. Due to the impacts associated with nutrient
accumulation in global waters, WWTPs are heavily regulated to reduce the loadings associated
with the plant effluent.
1.2 Point Source Discharges in Wisconsin
The Wisconsin Department of Natural Resources (WDNR) regulates point source discharges to
the environment across the State of Wisconsin. Facilities discharging wastewater treatment plant
effluent to surface waters, or groundwater, are individually regulated to specific permits for the
facility. The Wisconsin Pollutant Discharge Elimination System (WPDES) permit is issued to
facilities on a five year cycle. Point source dischargers, such as Nine Springs Wastewater
Treatment Plant (NSWWTP) in Madison, WI, are required to monitor and discharge effluent below
criteria established for a number of parameters that can vary seasonally. In order to maintain water
quality standards in which the facility discharges to, NSWWTP effluent is permitted on discharge
related to BOD5, TSS, DO, pH, Total Phosphorus, fecal coliforms, nitrogen as ammonia, chlorides,
and mercury. The full WPDES permit for NSWWTP is provided in Appendix B. NSWWTP is
currently not permitted on the basis of Total Nitrogen (TN), however these limits are becoming
increasingly common across the state and the facility is anticipating TN limits in coming permit
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terms. Of specific interest related to this research, the NSWWTP, like other municipal facilities in
Wisconsin, is required to discharge effluent ammonia to stringent limits that vary seasonally, as
well as daily, weekly, and monthly. The variability in limits is due to the facility’s established
design criteria and the Department’s modeling of the surface water in which effluent is discharged
to, which typically is based on generic assumptions, but can be updated to site specific criteria
based on instream testing and monitoring. The limit calculation by the Department separates the
months of the year into the growing season to include May through September, when stream
temperatures are the highest. The effects of increased temperature also dictate the percent mixing
that the effluent plume has with the receiving waters. Therefore, during the growing season,
effluent limits become more stringent to reduce eutrophication effects and due to the assumed
dilution effects with the receiving water being greater than those during cold water months. As
such, the NSWWTP is permitted for effluent ammonia based on a daily maximum that applies
year round, a weekly average which is different during the growing season, and a monthly average
which is also different during the growing season. Table 1.2.1 summarizes these limits. It should
be noted that NSWWTP is unique in that the facility operates with two effluent outfalls, that each
have different effluent criteria. The full scale plant treats all of the effluent to the more stringent
criteria, presented in Table 1.2.1, which is to the discharge into Badger Mill Creek, located in the
town of Verona, WI.
Table 1.2.1 Permitted effluent limits at NSWWTP for ammonia
Parameter Limit Type Limit and Units Notes
Nitrogen, Ammonia
(NH3-N) Total
Daily Max 11 mg/L Limit applies year-round
Weekly Avg 8.7 mg/L Limit applies October-April
Weekly Avg 2.6 mg/L Limit applies May-September
Monthly Avg 3.8 mg/L Limit applies October-April
Monthly Avg 1.1 mg/L Limit applies May-September
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The effluent limits provided in Table 1.2.1 were applicable during the research presented within
this thesis, however based on the cyclical process of permit renewals and permit evaluations, the
limits are subject to change each term. The Wisconsin State Legislature also mandates no waters
in the state shall be lowered in quality, a term defined as antidegradation in NR 102.0526. The
result of antidegredation requirements on point source dischargers means that the limits in the
current permit cannot become less stringent in future permits. As such, the NSWWTP will be
required to discharge effluent that is of this quality, or better for perpetuity. For that reason, it is
increasingly important to cost effectively and reliably remove nutrients from wastewater prior to
discharge into waters of Wisconsin.
1.3 Energy Usage for Wastewater Treatment
In conjunction with efforts to reduce direct impacts to the waterways in which WWTPs discharge,
a parallel initiative to reduce energy consumption at WWTPs has been pushed to the forefront of
operational goals. It is well recognized that the mechanical processes in which aerated conditions
are developed in activated sludge treatment account for 50% or more of the WWTP operating
costs31. Extensive research has been performed related to efforts in reducing the aeration
requirements at WWTPs2, 3, 4, 33. Conventional biological nutrient removal (BNR) utilizing
activated sludge treatment has historically targeted a dissolved oxygen (DO) concentration of 2
mg/L. By reducing the target DO concentration, less energy is required to add air to the treatment
process. At NSWWTP previous studies have shown potential energy savings exceeding $200,000
per year for low DO operations6. Typically, air is added to the biological system by means of
diffused aeration with compressed air blowers, or top mounted mechanical aerators which rotate
to develop turbulence and introduce oxygen. If the aeration blowers or mechanical aerators can
operate at reduced speeds, and thus lower electrical loads, a cost savings is introduced in
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comparison to conventional treatment practice. Although continuously aerated secondary
treatment is considered conventional when discussing activated sludge treatment, cases for energy
savings of upwards of 50% exist when an intermittent scheme is implemented32. The DO within
an activated sludge system is utilized by microorganisms which consume organic and inorganic
substrates in the waste stream by using oxygen as an electron acceptor. When oxygen is limited
within the system, some microorganisms are able to use other acceptors, but not in sufficient
capacity to remove all oxygen inputs from the engineered system. Therefore, although full scale
anaerobic treatment may provide substantial costs savings, the processes are not fully understood
and full scale capable yet. One avenue being explored includes ammonia oxidation through
sulphidogenesis, where ammonia uses sulphate as an electron acceptor25.
1.4 Conventional Process Control Schemes
WWTPs across the world utilize the addition of air, and thus oxygen, to the water to provide an
electron acceptor for the oxidation of reduced substrates in the wastewater. Conventional design
and operation of WWTPs target DO concentrations of 2 mg/L to provide sufficient oxygen for
microbial usage. In states like Wisconsin, the aeration equipment at a WWTP is even mandated to
be capable of maintaining a dissolved oxygen concentration of 2 mg/L within the aerobic mixed
liquor per NR110.2126. Therefore, extended aeration such as an oxidation ditch, as well as
conventional activated sludge treatment trains are designed and often operated above DO
concentrations of 2 mg/L. The traditional process of oxidation ditch aerators and activated sludge
blowers utilize DO controls and variable frequency drives (VFDs) to ramp the equipment output
based on demand. With DO probes in the process tankage, supervisory control and data acquisition
(SCADA) communications allow the operator to select a target DO concentration which the
equipment then seeks to operate at. That is, if a setpoint of 2 mg/L is established, the VFD will
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ramp the blower or ditch aerator motor to increase and/or decrease the output based on the demand
in the tank. Another process configuration specifically for activated sludge treatment plants with
process air blowers is the utilization of most open valve (MOV) control. Plants which utilize MOV
for the aeration process have modulation of electric valves on the air headers, in addition to the
ramping of the blowers on VFDs. While one basin may require more air to hit a DO setpoint, the
modulation of the valve will open which normally would decrease the overall system pressure.
However, with the pressure sensor on the air header, the blower ramps up to maintain a pressure
setpoint. This control strategy prevents valve movement at one basin from effecting the rest of the
system5. One relatively unconventional strategy for full scale operation, but often used in research,
is the intermittent aeration strategy controlled with ammonia setpoints. By aerating to provide
enough treatment of ammonia then eliminating aeration for durations of time, energy savings exist
and residual carbon is maintained to promote denitrification27. Because of the efforts devoted to
energy savings as outlined previously, the conventional treatment practice is being tested and
optimized by experimenting and piloting new ideas to provide aeration capacity for sufficient
treatment year round, while reducing costs.
1.5 Temperature Effects on Wastewater Treatment
WWTP performance and operational stability can often be attributed to ambient conditions and
temperatures. Although generally the highest wastewater temperatures occur at the upper ends of
the sewerage system, nearest the consumers, heat exchange through the conveyance system and a
net loss in heat occurs as the waste is conveyed to the treatment facility8. In locations where
ambient conditions change with seasons, the influent and operating temperatures of the secondary
treatment processes can drastically impact performance, especially nitrification. Due to the losses
through the sewerage conveyance system and impacts of ambient temperatures on uncovered
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process tanks, ammonia oxidizing bacteria (AOB) growth rates, and thus nitrification rates, are
substantially decreased. Modeling efforts for a WWTP in Zurich, Switzerland, where influent
temperatures regularly decrease to below 59 degrees Fahrenheit (15 degrees Celsius), have shown
that a decrease in influent temperature that occurs over the period of hours results in no loss of
nitrification due to equalization effects in the process tanks. However, when a permanent decrease
in temperature, over a period of days, is observed, a decrease of 1 degree Celsius leads to a 10%
reduction in the maximum specific growth rate of the nitrifying bacteria8. Additional temperature
impact studies have shown that both AOBs and nitrite oxidizing bacteria (NOBs) are partially
inhibited when wastewater temperatures range from 52 to 61 degrees Fahrenheit (11 to 16 degrees
Celsius). Conversely, at temperatures greater than 68 degrees Fahrenheit (20 degrees Celsius), no
inhibition is shown on the organisms and the AOB growth rate exceeds that of the NOB growth
rate10. The impacts that seasonal temperature variation have on the efficiency of ammonia
oxidation in wastewater treatment plants is important to note and understand when relating to
permitted effluent quality as described in Section 1.2. Although the WDNR recognizes the effects
of temperature and allows for less stringent ammonia limits during the winter, it is critical that the
operational strategy accommodates the decrease in nitrification during periods of decreased
temperature.
1.6 General Objectives of This Thesis
In conjunction with the Madison Metropolitan Sewerage District’s goals of achieving successful
nutrient removal with a low energy demand and reliable process28, a pilot scale reactor was set up
and operated to evaluate the reliability of low DO operation. By historically operating the pilot at
a fixed low DO concentration3 and recently manipulating the system to react to nutrient loads in
the wastewater, we have developed an early understanding of the accommodations needed to
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maintain year round treatment through this first iteration of pilot control. In addition, preliminary
identification of side effects of the low DO process and the low DO process supplemented with
ammonia based control have initiated discussion as additional design considerations for the
potential implementation on full scale treatment processes. The ultimate goal of the research
associated with the enhancements of the low DO pilot was to evaluate ammonia removal year
round through the addition of ammonia-based aeration controls. To address the overall objective,
this thesis work had the following goals:
1. Identify the primary factors influencing nutrient removal while operating at low DO
conditions year round with specific interest in maintaining nutrient removal during cold
weather operational periods.
2. Create and implement a control strategy which can react to nutrient loadings while still
having the ability to utilize a low DO operation.
3. Address changes related to nutrient removal efficiency and simultaneous nitrification and
denitrification between the operations with and without ammonia-based controls.
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CHAPTER 2: MATERIALS AND METHODS
2.1 Pilot Plant Process Configurations
The pilot scale plant at Nine Springs Wastewater Treatment Plant (NSWWTP) was reconstructed
and seeded in 2014 and has been in operation with two configurations since June 4th, 2014.
Initially the process was configured as a University of Cape Town (UCT) process without nitrate
recycle. Only one internal recycle was used which provided biomass from the end of the anoxic
zone to the head of the anaerobic zone. A typical UCT process utilizes an additional internal
recycle pump which provides nitrates from the end of the aerobic zone, to the anoxic tank for
denitrification. The pilot process excluded this additional recycle to utilize a less energy intensive
process, and because the full scale plant is not regulated for TN removal. Figure 2.2.1 presents the
UCT pilot configuration.
Figure 2.2.1 UCT pilot configuration schematic and details
The basis for design and configuration of the pilot scale reactor was to simulate the configuration
at full scale, but operate with low DO conditions in the aerated portion of the plant. For a period
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of approximately nine months during 2015 to 2016, the pilot was operated as a Johannesburg
Process. The Johannesburg Process pumps RAS to a pre-anoxic tank at the head of the process to
denitrify RAS prior to the anaerobic zone where nitrates can limit the efficiency of biological
phosphorus removal. A recycle stream provides water high in nitrates from the end of the aerobic
zone, to a second anoxic tank which follows the anaerobic zones. The nine month duration of
operation as a Johannesburg Process resulted in excessive foaming and unsuccessful nutrient
removal. It is suspected that a combination of the configuration, low DO conditions, and cold water
temperature resulted in the process upsets which included poor effluent quality, bad settling sludge
in the final clarifier, and foaming sludge which created operational issues related to scum removal
and recycle pumping. Figure 2.2.2 presents the process schematic for the pilot operated with the
Johannesburg configuration.
Figure 2.2.2 Johannesburg pilot configuration schematic and details
Nonetheless, as of June 10th, 2016 the process reverted back to the UCT which has been the
representative process since then. From this point forward, all data, results and discussion will be
relevant to the UCT configuration only.
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2.2 Pilot Plant Operations
The pilot was established to experimentally test the possibility and reliability of operating
a BNR process under low DO conditions. In using a Modified UCT configuration, an anaerobic
zone, anoxic zone, and aerobic zone is developed. Influent is fed to the head of the plant, which is
the first anaerobic tank of three in this pilot plant. Following the third anaerobic tank is a single
anoxic tank where no oxygen is added, but instead the tank is introduced RAS for heterotrophic
denitrification to occur. At the end of the anoxic zone, a recycle pump distributes biomass to the
head of the plant where biomass can be introduced to the anaerobic zone with little to no nitrates
available. This develops a truly anaerobic condition for biological phosphorus release to occur in
the phosphorus accumulating organisms (PAOs).
In order to target successful phosphorus and ammonia removal, the plant was constructed
and operated with various important parameters. Influent to the pilot is pumped from a pipe tap
off the NSWWTP full scale primary clarifier effluent such that nutrient loadings to the pilot
generally trend with what full scale operations see. To achieve a secondary treatment HRT similar
to the full scale NSWWTP (12 hours), the influent was pumped to the first anaerobic tank at a rate
of approximately 0.9 gpm (3.4 L/min) which yielded an average of a 7.7 hour HRT. Aside from
adding volume to the treatment process, the pumped flow could be reduced but issues with flow
velocities and line clogging occur. The anaerobic zone of the pilot plant consists of three tanks,
each completely mixed with a vertical shaft mixer mounted above the tank, and provides
approximately 80 gallons (303 liters) of treatment volume. Following anaerobic conditions, a
single 105 gallon (398 liters) anoxic zone is created by mixing RAS with anaerobic zone effluent.
The final three treatment tanks are the aerobic zone, providing 315 gallons (1192 liters) of
treatment where BOD removal, ammonia oxidation, and phosphorus uptake occur. Air was
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introduced to each of the three aerobic tanks through a fine bubble diffuser approximately 4 feet
(1.2 meters) below the water surface. Flow to each diffuser was manually controlled with an
individual air flow meter feeding each diffuser. The concluding process of final clarification is
done in a 268 gallon (1014 liters) conical tank where mixed liquor is introduced in an effort to
settle biomass from treated effluent prior to discharge from the pilot plant. The internal recycle
flow from anoxic to anaerobic was fixed at a flowrate equal to the influent feed of approximately
0.9 gpm (3.4 L/min). RAS flow from the final clarifier to the anoxic zone was fixed at a flowrate
just less than two times the influent feed, thus at approximately 1.7 gpm (6.4 L/min). Solids were
wasted from the third aerobic tank as WAS, to control an SRT of 10 – 12 days which has been
previously used in the pilot to accommodate AOBs growth and to achieve nitrification at low DO
conditions6. Using Equation 1 with a known target SRT, the required WAS flow rate was
calculated based on pilot reactor configuration and lab results for TSS concentrations. WAS
pumping occurred for an average of 1.3 hours per day, which increased during summer and
decreased during winter, resulting in approximately 31 gallons (117 liters) of mixed liquor
removed from the pilot daily. The following equation was used for calculating SRT in the pilot,
where Q is flow in gpd, TSS is in mg/L, and V is in gallons. Influent flow to the pilot was fixed
and the pilot was generally operated as a chemostat, thus effluent flow was assumed to be equal to
influent flow. TSS for aerobic, anaerobic, WAS, and effluent conditions were taken three times
per week and analyzed at the UW lab for results. Tank volumes were known based on cylindrical
geometry with known diameters and known operating depths. WAS flow was then manually
adjusted with a time controller to achieve the required volume of mixed liquor to be removed to
achieve the desired SRT.
15
Equation 1:
𝑆𝑅𝑇 = (( V
Anoxic+VAerobic) * TSSAerobic)+( VAnaerobic * TSSAnaerobic)
( QWAS
* TSSWAS)+(( Qin
- QWAS
)* TSSEffl)
2.3 Pilot Plant Process Control
Process control sensors were used within the pilot to control DO conditions and to monitor
ammonia within the mixed liquor. A YSI FDO 701 optical dissolved oxygen sensor was installed
in aerobic tank 2, shown in Figure 2.3.1, for the duration of the pilot plant operations to monitor,
trend, and control DO concentrations in the aerobic zones. The sensor range of measurement spans
from 0 to 20 mg/L with 0.01 mg/L resolution. Accuracy of the sensor is reported as ±0.05 mg/L
when the DO is less than 1 mg/L and ±0.1 mg/L when the DO is greater than 1 mg/L. The technical
data of the sensor also notes a t90 response time of less than 60 seconds and a t95 response time of
less than 80 seconds. Response times denote the length of time that it takes for the probe to output
the specified fraction of the final response. That is, a t90 specifies the time it takes for the probe to
reach 90% of its final value and t95 specifies the time it takes for the probe to reach 95% of its final
value. Shorter response times allow for more real-time data, with less delay to reach the final
output value. The DO probe was interfaced with the IQ Sensor Net system for control, trending,
and monitoring of the concentration within aerobic tank 2. The DO probe also provided water
temperature data for trending. This sensor historically controlled the DO to a setpoint of 0.5 mg/L,
by which a single air solenoid valve would open and close to provide or limit air flow to maintain
the setpoint concentration. Air flow to the adjacent aerobic tanks, 1 and 3, were not directly
controlled by a DO setpoint, but were manually adjusted with air flow meters to provide a DO
gradient from tank 1, to tank 2, to tank 3 that typically operated at 1 mg/L, 0.5 mg/L, and 0.3 mg/L,
respectively.
16
In September 2017, an additional online probe was introduced to the pilot plant process. A
YSI AmmoLyt Plus 700 IQ modular sensor was placed in aerobic tank #3 to monitor and trend
ammonia concentrations, with the ultimate goal to use ammonia sensing to control DO conditions.
It should be noted that the sensor measures ammonium, NH4+, which is nontoxic and not of the
concern that ammonia, NH3, is. The YSI AmmoLyt probe measures ammonium but then totalizes
to the ammonia value output used in this analysis based on pH and temperature. Ammonium is
able to be measured between 0.1 and 129 mg/L with 0.1 mg/L resolution. The t90 response time
for the probe is less than 3 minutes. Data from the probe was available in real time and used to
trend diurnal variations of ammonia within the aerobic mixed liquor. After an extended trial of the
ammonia probe output, the sensor was configured to control the operator adjustable DO setpoints,
to develop the first attempt at ammonia-based aeration control for the pilot plant at NSWWTP.
The process control prior to the implementation of ammonia-based aeration controls used
the optical DO sensor and a single solenoid valve on the air distribution header to allow or restrict
air flow into the aerobic tanks based on the operator adjustable DO setpoint. Once the low DO
configuration was established at 0.5 mg/L DO, this parameter remained unchanged until the next
evolution of controls was implemented. A schematic of the UCT process control and aeration
distribution is presented in Figure 2.3.1.
17
Figure 2.3.1 UCT process control and aeration schematic
Simple conditions and criteria for ammonia-based aeration controls were created and
implemented in an attempt to maintain nitrification through periods of cold water operation. The
control strategy was developed to provide a simple process which allows for ease of operator
intervention. The pilot controls were subsequently divided into two different modes; low DO mode
and high DO mode. The controls were established such that in low DO mode, if the ammonia
readings in the mixed liquor were below an operator adjustable value, then the plant would operate
at a DO setpoint of 0.5 mg/L in aerobic tank #2. Conversely, if the ammonia value exceeds the
desired value in the mixed liquor, the pilot will switch to a high DO mode which operates at a DO
setpoint higher than 0.5 mg/L in aerobic tank #2, in an effort to provide sufficient air for the AOB
community when oxidation rates are decreased. The evaluation of the controls included one change
in the ammonia setpoint and two changes in the high DO setpoint. The ammonia setpoint was
changed from 3 mg/L to 1 mg/L and the high DO setpoint was adjusted between 1.0 mg/L and 1.5
mg/L. This summary of control setpoint changes is provided below in Table 2.3.1.
18
Table 2.3.1 Ammonia-based aeration control setpoint changes summary
Days of NH3
Controls Event
0 NH3 Setpoint - 3.0 mg/L
High DO Setpoint 1.0 mg/L
9 NH3 Setpoint - 1.0 mg/L
39 High DO Setpoint - 1.5 mg/L
79 High DO Setpoint - 1.0 mg/L
100 High DO Setpoint - 1.5 mg/L
111 Pilot taken offline
2.4 Pilot Plant Maintenance & Sampling
The pilot plant was inspected and maintained 6 days per week (Monday – Saturday) and
samples were taken at various locations across the process 3 days per week (Tuesday, Thursday,
Saturday). Routine maintenance of the pilot included a 30-minute settling test for sludge volume
index (SVI) calculations, pump calibrations and tubing replacements, clarifier scum skimming,
and DO spot checks with a handheld WTW Multi 3410 Multiparameter Meter with FDO 925-6
DO probe to verify the permanent DO probe performance and accuracy. Clarifier scum waste was
totaled and recorded for each day the maintenance was performed, however these wasted solids
were not included within the SRT calculations and subsequent WAS flow rate determinations. On
days when sampling occurred, numerous samples were collected and prepared for analysis at either
the NSWWTP Laboratory or the Environmental Engineering Laboratory at UW-Madison. Influent
(filtered and unfiltered), effluent (filtered), and total suspended solids (TSS) samples were
regularly collected from the pilot. Additionally, a weekly biomass sample was saved from both the
pilot and the full scale plant for preserving and future microbial analysis. On a biweekly (once
every other week) schedule, a full nutrient profile sampling procedure occurred and a grab sample
from each tank of the pilot process was filtered and analyzed. Routine grab samples for influent
19
and effluent were sampled at the UW-Madison lab for a number of parameters including NH3,
NO2-, NO3
-, acetate, PO43-, and COD. Ammonia and phosphate analysis utilized HACH Test ‘N
Tube methods and a spectrophotometer to determine the resultant nutrient concentrations. Nitrate,
nitrite, and acetate samples were analyzed using a high-performance liquid chromatography
(HPLC) machine in the lab following standard procedure methods29. COD was analyzed through
the USEPA Reactor Digestion Method, Method 8000. Also completed in the University lab on a
regular basis was TSS and VSS analysis, both following standard methods29. TSS samples were
taken from the second anaerobic tank, second aerobic tank, RAS, WAS, and effluent. The
NSWWTP lab provided results for TKN and TP for the biweekly profile sampling of influent,
anaerobic tank #1, #2, and #3, anoxic, aerobic tanks #1, #2, and #3, and pilot effluent. Additional
nutrient calculations used the aforementioned sample results such as TN, NOx (the sum of nitrates
and nitrites), and simultaneous nitrification and denitrification (SND) whose equations are
provided below.
Equation 2:
𝑇𝑁 = 𝑇𝐾𝑁 + 𝑁𝑂𝑥
Equation 3:
Where 𝑇𝐾𝑁 = 𝑂𝑟𝑔𝑎𝑛𝑖𝑐 𝑁 + 𝑁𝐻3
Equation 4:
And 𝑁𝑂𝑥 = 𝑁𝑂2− + 𝑁𝑂3
−
Equation 5:
𝑆𝑁𝐷 = (𝑇𝐾𝑁𝐴𝑛𝑜𝑥𝑖𝑐 + 𝑁𝑂𝑥𝐴𝑛𝑜𝑥𝑖𝑐) − (𝑇𝐾𝑁𝐴𝑒𝑟𝑜𝑏𝑖𝑐 3 + 𝑁𝑂𝑥𝐴𝑒𝑟𝑜𝑏𝑖𝑐 3)
20
Influent and effluent loadings were calculated to determine the pounds of nutrients or
oxygen demand entering and leaving the process. The equation used for determination of load is
presented below.
Equation 6:
𝑙𝑏𝑠
𝑑𝑎𝑦=
𝑚𝑔
𝐿∗ 𝑀𝐺𝐷 ∗ 8.34 (
𝑙𝑏𝑠
𝑔𝑎𝑙)
As noted above, SVI calculations were routinely performed to evaluate the settling
characteristics of the sludge entering the clarifier. The equation used for the calculation is
presented below.
Equation 7:
𝑆𝑉𝐼 (𝑚𝐿
𝑔) =
𝑆𝑒𝑡𝑡𝑙𝑒𝑑 𝑆𝑙𝑢𝑑𝑔𝑒 𝑉𝑜𝑙𝑢𝑚𝑒 (𝑚𝐿𝐿 ) ∗ 1000 (
𝑚𝑔𝑔 )
𝑀𝐿𝑆𝑆 (𝑚𝑔
𝐿 )
Additional data used in Chapter 3, not from lab results, include 15-minute DO and
temperature values from the permanent probe in aerobic tank 2, 15-minute NH3 data from the
permanent probe in aerobic tank 3, and 5-second on/off air solenoid data from the valve feeding
air to the plant. In general, DO and NH3 data is used for trending and discussions only. Conversely,
air solenoid data was summarized per day resulting in a duration per day that the air valve was
open and air was being fed to the system. The intermittent aeration scheme with the plant thus can
be divided into time air was added and time air was restricted, per day. Using the fixed flow air
flow meter readings recorded each day with daily maintenance cycles, a standard cubic feet per
day (SCFD) calculation can be made which was converted to pounds of air per day, at standard
conditions, for each of the three aerobic zones using a density of air of 0.075 pounds per cubic
21
foot. Furthermore, the mass of air added to each aerobic tank was broken down to the mass of just
oxygen added to each tank, using an atmospheric oxygen makeup of 21%.
Equation 8:
𝑂𝑥𝑦𝑔𝑒𝑛 𝑖𝑛𝑝𝑢𝑡 𝑡𝑜 𝑎𝑒𝑟𝑜𝑏𝑖𝑐 𝑡𝑎𝑛𝑘 (𝑙𝑏𝑠
𝑑𝑎𝑦@ 𝑆𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝐶𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛𝑠) =
𝑆𝑜𝑙𝑒𝑛𝑜𝑖𝑑 𝑉𝑎𝑙𝑣𝑒 𝑂𝑝𝑒𝑛 (𝑠𝑒𝑐𝑜𝑛𝑑𝑠) ∗ 1 𝑚𝑖𝑛
60 𝑠𝑒𝑐𝑜𝑛𝑑𝑠∗ 𝐹𝑙𝑜𝑤 𝑚𝑒𝑡𝑒𝑟 (𝑆𝐶𝐹𝑀) ∗ 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 (
𝑙𝑏𝑠
𝑓𝑡3) ∗ 21%
Based on oxygen demands for the oxidation of BOD and ammonia of 1.1 and 4.6 pounds
per pound (0.5 and 2.1 kg), respectively1, the inputs to the system were evaluated to determine if
the aeration provided was theoretically sufficient.
22
CHAPTER 3: RESULTS AND DISCUSSION
The desire to supplement a low DO activated sludge treatment process with ammonia-based
aeration controls is two-fold: reliable nutrient removal and reduction in energy consumption. The
results and associated discussion of this pilot scale study are presented by evaluating the
effectiveness of implementing controls to the existing pilot configuration, covering the SND and
TN effects of increased aeration due to the controls, and reviewing how process changes impact
treatment by evaluating weekly profile samples.
3.1 Influent Conditions
Daily samples are taken and analyzed by the NSWWTP staff and lab for a variety of nutrients and
water quality indicators following the full scale primary clarification process. In general, the results
of these samples represent the influent conditions to the pilot plant. Presented below in Table 3.1.1
is a monthly summary of nitrogenous influent parameters, from July 2017 to February 12th, 2018,
to present the changing conditions from warm water operation to cold water operation. Table 3.1.2
provides additional influent parameters measured by the NSWWTP. A full monthly summary is
included in the Supplementary Tables section, Table S.1. All of the influent parameters, aside from
total phosphorus, show a consistent increase in concentration, and thus load, being introduced to
the pilot plant for the duration of experimentation. Loading was calculated using Equation 6, with
data from NSWWTP lab results, and a fixed influent flow rate to the pilot of 0.9 gallons per minute.
Of particular interest is the greater than 50% increase in influent ammonia to the pilot plant feed
in addition to the approximately 83% increase in BOD5 over the 7.5 month influent conditions
summary. Although the seasonal trends of increased BOD5 and NH3-N concentration during winter
months are common, the concentrations seen into 2018 are the highest since 2016. Conversely,
23
2016 had the highest concentrations of TP, which have decreased and remained constant since
then.
Table 3.1.1 Monthly average summary for nitrogenous influent conditions from NSWWTP Lab
Month - Year TKN
(mg/L)
TKN
(lbs/day)
NH3-N
(mg/L)
NH3-N
(lbs/day)
Organic N
(mg/L)
Organic N
(lbs/day)
July-17 34.8 ± 3.9 0.37 ± 0.08 23.7 ± 3.7 0.25 ± 0.06 10.7 ± 2.4 0.12 ± 0.03
August-17 38.9 ± 2.0 0.42 ± 0.02 26.5 ± 1.4 0.29 ± 0.02 12.3 ± 1.5 0.13 ± 0.02
September-17 42.8 ± 3.3 0.47 ± 0.04 28.6 ± 2.6 0.31 ± 0.03 14.2 ± 2.1 0.15 ± 0.02
October-17 45.9 ± 2.7 0.47 ± 0.10 32.6 ± 2.5 0.34 ± 0.03 11.4 ± 8.5 0.12 ± 0.09
November-17 48.4 ± 2.9 0.53 ± 0.03 34.1 ± 2.8 0.37 ± 0.03 14.3 ± 2.0 0.16 ± 0.02
December-17 49.8 ± 2.8 0.54 ± 0.03 34.6 ± 2.2 0.38 ± 0.02 15.2 ± 2.7 0.17 ± 0.03
January-18 50.4 ± 3.0 0.55 ± 0.03 35.0 ± 2.8 0.38 ± 0.03 15.4 ± 1.9 0.17 ± 0.02
February-18 54.3 ± 3.5 0.37 ± 0.04 35.8 ± 2.0 0.21 ± 0.15 24.5 ± 2.5 0.17 ± 0.08
Average 46.5 ± 3.0 0.47 ± 0.05 32.1 ± 2.5 0.32 ± 0.05 14.4 ± 2.9 0.15 ± 0.04
Table 3.1.2 Monthly average summary for various influent conditions from NSWWTP Lab
Month - Year BOD5
(mg/L)
BOD5
(lbs/day)
Total P
(mg/L)
Total P
(lbs/day)
July-17 122.1 ± 21.4 1.28 ± 0.33 4.9 ± 0.5 0.05 ± 0.01
August-17 143.0 ± 18.7 1.56 ± 0.20 5.9 ± 0.6 0.06 ± 0.01
September-17 145.2 ± 20.4 1.58 ± 0.22 6.4 ± 0.6 0.07 ± 0.01
October-17 167.8 ± 18.1 1.77 ± 0.20 6.3 ± 0.6 0.06 ± 0.01
November-17 178.8 ± 21.8 1.94 ± 0.24 6.4 ± 0.5 0.07 ± 0.01
December-17 181.3 ± 26.7 1.97 ± 0.29 6.1 ± 0.6 0.07 ± 0.01
January-18 198.3 ± 22.9 2.16 ± 0.25 6.2 ± 0.4 0.07 ± 0.01
February-18 224.3 ± 36.8 1.16 ± 0.40 6.5 ± 0.6 0.04 ± 0.01
Average 171.7 ± 23.3 1.70 ± 0.27 6.2 ± 0.5 0.06 ± 0.01
In addition to the rising influent nutrient loading during the period of interest, water temperatures
trended with seasonal ambient conditions, and decreased by approximately 44% from September
2017 to February 2018. Figure 3.1.1 depicts the monthly average trends that the pilot plant
experienced in regards to influent concentration and temperatures.
24
Figure 3.1.1 Monthly average influent concentrations and seasonal temperature variation
The sampling regiment described in Chapter 2 resulted in samples for analysis at the University of
Wisconsin-Madison Environmental Engineering Lab. Shown in Table 3.1.3, is the phosphate
testing performed at the University. It should be noted that the phosphorus results presented in
Table 3.1.2 from NSWWTP are total phosphorus, and phosphorus values in Table 3.1.3 from the
University lab are orthophosphate, or reactive phosphorus (PO43-). The orthophosphate analyzed
at the University Lab is also known as soluble reactive phosphorus, and is the form directly taken
up by cells. Total phosphorus is a sum of the dissolved and particulate forms of phosphorus in the
liquid stream. Comparison of the two tests over the duration presented results, on average, in
approximately 73% of the soluble reactive phosphorus makeup of the total phosphorus present.
0
50
100
150
200
250
0
5
10
15
20
25
30
35
40
Jul-17 Aug-17 Sep-17 Oct-17 Nov-17 Dec-17 Jan-18
BO
D5
(mg/L
)
NH
3-N
(m
g/L
) &
Tem
p (
C)
NH3 (mg/L) Temp BOD5 (mg/L)
25
Table 3.1.3 Monthly average summary for influent phosphate conditions from University of Wisconsin-
Madison Environmental Engineering Lab
Month - Year PO4
3-
(mg/L)
PO43-
(lbs/day)
July-17 4.0 0.04
August-17 4.9 0.05
September-17 4.0 0.04
October-17 5.3 0.06
November-17 4.4 0.05
December-17 4.0 0.04
January-18 4.4 0.05
February-18 4.3 0.03
Average 4.4 0.05
3.2 Temperature Influences on Pilot Performance
Throughout the pilot operation, temperature decrease commonly coincided with reduced effluent
quality, specifically in regards to ammonia. In general, the process upsets associated with poor
ammonia removal on the low DO pilot reactor occurred during periods in which the liquid
temperatures decreased below 17 degrees Celsius. Figure 3.2.1 shown below provides a timeline
of effluent ammonia grab sample results and water temperature in the mixed liquor from July 2017
through March 2018. Presented in Appendix A, Figure S.1, is the timeline since the reconstruction
of the pilot. The reoccurring trends routinely related poor ammonia removal, hence reduced
nitrification, with low temperatures.
26
Figure 3.2.1 Historical summary of temperature fluctuations and nitrification upsets
A correlation analysis was conducted to determine the relationship that temperature had on effluent
ammonia concentration using Equation 9. Temperature data was defined by x, where �̅� was the
sample mean of the data. Effluent ammonia data was defined by y, where �̅� was the sample mean.
Equation 9:
𝐶𝑜𝑟𝑟𝑒𝑙𝑎𝑡𝑖𝑜𝑛 = ∑(𝑥 − �̅�)(𝑦 − �̅�)
√∑(𝑥 − �̅�)2 ∑(𝑦 − �̅�)2
Due to the nature of the relationship, a negative one (-1) value for correlation would indicate a
perfect negative correlation, where if temperature, x, decreases, then ammonia, y, would increase.
The result of the calculation, using data from July 2017 through February 2018, indicated a
correlation of -0.45. Figure 3.3.2 presents the correlation data graphically. It is evident that when
temperature is reduced, the frequency of poor removal and magnitude of effluent concentrations,
is greater than during periods of warmer wastewater temperatures.
0
5
10
15
20
25
30
0
5
10
15
20
25
July-17 September-17 October-17 December-17 January-18 March-18
Wat
er T
emp
(C
)
Effl
uen
t N
H3-
N (
mg/
L)
NH3-N (mg/L) Temp
27
Figure 3.2.2 Correlation analysis of wastewater temperature and effluent ammonia concentration
Prior to the implementation of ammonia-based aeration controls, ammonia oxidation was typically
stable and successful during warm water periods. Shown below in Figure 3.2.3, is effluent grab
sample results from July through September 2017. The sample results during this time frame
average to an effluent ammonia concentration of 0.52 mg/L. Historically, the pilot effluent in
regards to ammonia follows the same seasonal trends shown through the summer of 2017.
Figure 3.2.3 Effluent grab sampling results for NH3-N concentration during warm water operations
3.3 Ammonia Tracking
Upon installation of an ammonia probe in aerobic tank #3, a period of approximately 3 months
was observed prior to the startup of the ammonia-based controls. The resulting data was used to
understand how variable the ammonia concentration within the mixed liquor was throughout time.
0
2
4
6
8
10
12
14
16
18
12 14 16 18 20 22 24 26 28
NH
3-N
(m
g/L
)
Temperature (Degrees C)
0
1
2
3
4
5
6
7
8
Jul-17 Aug-17 Sep-17 Oct-17
NH
3-N
(m
g/L
)
28
Figures 3.3.1 to 3.3.4 show the ammonia trends from September 14th, 2017 through December
12th, 2017, with 15-minute data points. Initially, a peak of ammonia concentration was observed
in late September, due to an unknown source, as shown in Figure 3.3.1. Various potential reasons
exist including probe fouling, septic receiving shock loads, or internal plant loads. Further,
multiple instances of equipment failure or malfunction caused large peaks of ammonia
concentration and should be noted. In early October, as shown in Figure 3.3.2, an ammonia peak
occurred due to a RAS pump failure and thus an accumulation of biomass within the final clarifier.
The accumulation of the biomass in the clarifier, without the RAS flow for redistribution of solids
to the aerobic zone, left insufficient concentrations of biomass in the aerobic tanks to perform
ammonia oxidation. Once remediated, the system response occurred within 48 hours which
included over 10 hours of pumping the accumulated solids and allowing the redistribution
throughout the aerobic tanks based on each tanks hydraulic residence time. It is assumed that the
remaining time of approximately 38 hours entailed the rapid, but limited, consumption of the high
ammonia residual due to the biomass uptake rates. Shortly after, on October 11th, the NSWWTP
introduced a centrate stream from the full-scale plant biosolids processing stream to the pilot
influent feed source, likely resulting in the increased loadings. Centrate loadings from biosolids
dewatering often contain concentrations of ammonia an order of magnitude higher than typical
raw influent concentrations24. In the end of November, shown on Figure 3.3.3, a failure associated
with the internal recycle pump caused an ammonia spike. Without the internal recycle, biomass
was not distributed to the anaerobic zone, so no substantial nutrient reduction occurred prior to the
anoxic tank. Thus, aeration was needed for increased carbon and ammonia loads, and the pilot
could not sufficiently maintain treatment. Finally, within the first week and a half of December,
shown on Figure 3.3.4, fine bubble membrane diffuser fouling resulted in insufficient air delivery
29
to the mixed liquor for stable nitrification. During this period, the low DO setpoint of 0.5 mg/L
could not be achieved and dissolved oxygen concentrations averaged just 0.3 mg/L. In general, it
was determined that daily fluctuations of 0 to 10 mg/L ammonia occur within the aerobic mixed
liquor and variability down to the hourly time scale often exists.
Figure 3.3.1 15-minute ammonia data within aerobic mixed liquor for the month of September 2017
Figure 3.3.2 15-minute ammonia data within aerobic mixed liquor for the month of October 2017
0
1
2
3
4
5
6
7
8
9
14-Sep 16-Sep 18-Sep 20-Sep 22-Sep 24-Sep 26-Sep 28-Sep 30-Sep
Co
nce
ntr
atio
n (
mg/L
)
0
5
10
15
20
25
30
1-Oct 6-Oct 11-Oct 16-Oct 21-Oct 26-Oct 31-Oct
Co
nce
ntr
atio
n (
mg/L
)
30
Figure 3.3.3 15-minute ammonia data within aerobic mixed liquor for the month of November 2017
Figure 3.3.4 15-minute ammonia data within aerobic mixed liquor for the first 12 days of the month of December 2017
During the ammonia tracking period from September to December, the pilot was operated at the
previously described control of intermittent aeration maintaining a low DO setpoint of 0.5 mg/L
within aerobic tank #2. The period of operations during which ammonia trending was observed
shed valuable information on the constant fluctuations of nutrient concentration within the mixed
liquor. This data also suggests that the grab sampling results and analysis should be used with
caution due to the hourly variability within the process. For example, Figure 3.3.5 below presents
0
2
4
6
8
10
12
14
16
18
20
1-Nov 6-Nov 11-Nov 16-Nov 21-Nov 26-Nov 1-Dec
Co
nce
ntr
atio
n (
mg/L
)
0
2
4
6
8
10
12
14
16
1-Dec 3-Dec 5-Dec 7-Dec 9-Dec 11-Dec 13-Dec
Co
nce
ntr
atio
n (
mg/L
)
31
the trends seen over a 24 hour period on Sunday, October 22nd, 2017 where little variability in DO
concentration was present and no known mechanical or process influences existed. Depending on
when a grab sample could be taken, the results and associated process changes based on the sample
could be unnecessary and not representative. At approximately 9:30 AM sample results would
indicate effluent ammonia near 4 to 4.5 mg/L whereas samples at 4 PM would indicate effluent
around 3 mg/L.
Figure 3.3.5 Daily variability in ammonia within the mixed liquor for Sunday, October 22nd, 2017.
The variability in the efficiency of the low DO process and the associated grab sample results
indicated the need for optimization of the process. Further discussion and recommendation is
provided in Section 4.1.
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00
Co
nce
ntr
atio
n (
mg/L
)
DO Conc NH3 Conc
32
3.4 Ammonia-Based Controls Trending
Upon recognizing the often extreme variability in nutrient removal within the pilot, controls were
developed to use the ammonia probe outputs to control the target DO setpoint within aerobic tank
#2 and by association, the aeration across all 3 tanks. Figure 3.4.1 shows the nearly instantaneous
response to the commencement of the ammonia based aeration control strategy midway through
the day on December 12th, 2017. For figure clarity, the data points shown are hourly averages of
15 minute probe data. The target ammonia setpoint in aerobic tank 3 was 3 mg-N/L and in order
to achieve this concentration, the pilot was allowed to operate in a high DO mode of 1 mg/L and
a low DO mode of 0.5 mg/L. It should be noted that the decrease in ammonia during December
20th is due to an influent feed pump clog and thus no nutrient loading being delivered to the pilot
plant.
Figure 3.4.1 Start of ammonia based control strategy with NH3 setpoint of 3 mg/L and high DO setpoint of 1 mg/L
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0
1
2
3
4
5
6
7
8
9
10
11
12
12-Dec 13-Dec 14-Dec 15-Dec 16-Dec 17-Dec 18-Dec 19-Dec 20-Dec 21-Dec
DO
(m
g/L
)
NH
3-N
(m
g/L
)
NH3-N DO
High DO mode
Low DO mode
33
The response of the pilot to the initial control setpoints was successful and resulted in operation in
the high DO mode for approximately 4.5 days before reverting back to low DO mode to maintain
the residual ammonia concentration of 3 mg-N/L. Based on these first 9 days, at this level of
treatment compared to full scale operations and satisfying the NSWWTP permit limit, the effluent
quality would successfully meet the most stringent limit of the permit during October through
April, a monthly average of 3.8 mg-N/L. However, operating at this concentration leaves a
minimal buffer between permit compliance and violation. The subsequent operational setpoint
change thus reduced the ammonia setpoint to 1 mg-N/L. As presented below in Figure 3.4.2, this
change also proved successful for a period of time, while frequently fluctuating between high and
low DO operations to maintain a residual ammonia concentration of 1 mg-N/L.
Figure 3.4.2 Pilot response to a decreased ammonia setpoint of 1 mg/L while maintaining a high DO setpoint of 1 mg/L
Following December 25th, 2017, the ammonia concentrations drastically increased and the pilot
predominately operated in high DO mode. When comparing pilot operations to full scale treatment
and the plant permit limits, it is important to note that an increase in concentration to any level
above 3.8 mg-N/L from October through April poses a threat to the facility and compliance with
0
0.2
0.4
0.6
0.8
1
1.2
0
1
2
3
4
5
6
21-Dec 21-Dec 22-Dec 22-Dec 23-Dec 23-Dec 24-Dec 24-Dec 25-Dec 25-Dec 26-DecD
O C
once
ntr
atio
n (
mg/L
)
NH
3 C
once
ntr
atio
n (
mg/L
)
NH3 DO
34
the WPDES permit. Thus, an increase of residual ammonia to above 5 mg-N/L in one day would
generally require immediate operator intervention. It was observed based on a daily average
temperature summary provided in Figure 3.4.3 that December 25th, 2017 was the first day in which
average liquid temperatures decreased below 16 degrees Celsius.
Figure 3.4.3 Daily average wastewater temperatures during the month of December, 2017
Following the sharp increase in ammonia concentration within the mixed liquor, the pilot was
allowed to operate under the same controls to see if a recovery of nitrification was possible at
temperatures below 16 degrees Celsius. As shown in Figure 3.4.4, the daily average ammonia
concentrations averaged approximately 2 to 3 mg-N/L into early January. Then by January 12th
the ammonia began to sharply increase again. Following a peak on January 17th of 11.9 mg-N/L,
the high DO setpoint was increased from 1 mg/L to 1.5 mg/L on January 20th. The effort to combat
the high ammonia concentrations, caused by decreased nitrification and low temperatures, by
increasing the high DO setpoint provided little to no relief as the pilot continued to discharge high
effluent ammonia for a resulting monthly average in January of 3.96 mg-N/L based on 12 grab
samples during the month. Table 3.4.1 provides a monthly average temperature summary, which
0
5
10
15
20
25
Tem
per
ature
(D
egre
es C
)
Daily Avg Temp 16 Deg C
35
shows that following the December 25th temperature dip, wastewater temperatures were limited to
an average of approximately 14 degrees Celsius.
Table 3.4.1 Monthly average wastewater temperature summary
Month - Year Temp (Degrees C)
Sep-17 24.8
Oct-17 23.1
Nov-17 19.8
Dec-17 16.8
Jan-18 14.4
Feb-18 14.0
Figure 3.4.4 Daily average NH3 and DO during process upsets in January, 2018
Following the month of January 2018, the ammonia probe data became unstable and suspect,
diagnosed as due to an electrode failure. Data from the ammonia probe is not presented beyond
this point due to these errors and inaccuracies, as well as various tests with adjacent tanks not a
part of this treatment train.
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0
2
4
6
8
10
12
14
DO
(m
g/L
)
NH
3-N
(m
g/L
)
NH3 DO
36
3.5 Effects of Ammonia-Based Aeration Controls – Aeration Capacity
Through the implementation of ammonia-based aeration controls, the pilot received higher
oxygen loadings as ammonia effluent increased. By enabling the system to call for additional
oxygen when needed based on nutrient loading, more aeration supply was seen in comparison to
low DO operation, but less of the relative aeration capacity was utilized. The aeration capacity of
the pilot is dictated by the manual flow meter settings at each aerobic tank and the status of the
air solenoid valve. Full capacity utilization would require the air solenoid valve be open 24 hours
per day and thus the maximum amount of air would be distributed to each tank. Therefore in the
following figures, the maximum allowable input is denoted by a solid line which would indicate
the air solenoid valve is fully open all day and delivers the manually established flow rate to the
tank for the full 24 hours per day. Due to the intermittent aeration strategy however, the air
solenoid valve was closed for numerous periods throughout the day, which restricted the total
delivery to the system. Figures 3.5.1, 3.5.2, and 3.5.3 below summarize the amount of aeration
used per day in aerobic tank 2 compared to the allowable aeration input, dictated by the fixed
position of the flow meters at each diffuser feed pipe. In general, only aerobic tank 2 was utilized
for clarity and because this process tank was where the DO probe was located. However, when
changes to aerobic tank 3 occurred, the results are shown. No changes occurred in aerobic tank 1,
thus the data is not shown. In September, on average approximately 94% of the aeration capacity
was utilized, or in other words, the aeration solenoid valve was open 94% of the time on average
in September. Similarly, October utilized 90% of the available capacity and November 89%.
37
Figure 3.5.1 September 2017 pilot aeration capacity usage per day
Figure 3.5.2 October 2017 pilot aeration capacity usage per day
0
5
10
15
20
25
0
10
20
30
40
50
60
70
80
90
100
NH
3-N
(m
g/L
)
Lb
s A
ir/D
ay @
Std
Co
nd
itio
ns
Aerobic 2 Maximum Allowable Input Daily Avg NH3
0
5
10
15
20
25
0
10
20
30
40
50
60
70
80
90
100
10/1
10/2
10/3
10/4
10/5
10/6
10/7
10/8
10/9
10/1
0
10/1
1
10/1
2
10/1
3
10/1
4
10/1
5
10/1
6
10/1
7
10/1
8
10/1
9
10/2
0
10/2
1
10/2
2
10/2
3
10/2
4
10/2
5
10/2
6
10/2
7
10/2
8
10/2
9
10/3
0
10/3
1
NH
3-N
(m
g/L
)
Lb
s A
ir/D
ay @
Std
Co
nd
itio
ns
Aerobic 2 Maximum Allowable Input Daily Avg NH3
38
Figure 3.5.3 November 2017 pilot aeration capacity usage per day
The high level of capacity utilized from September through November was indicative of higher
oxygen demand which called for nearly constant aeration to maintain a low DO setpoint of 0.5
mg/L. Conversely, the implementation of the ammonia-based aeration controls saw a decrease in
the capacity utilization, but an overall net increase in air added to the pilot. Figures 3.5.4 and 3.5.5
show the significant gap between the actual aeration output and the maximum allowable input to
the aerobic zone. The gaps shown each day between the columns and the maximum input lines
indicate excessively intermittent operation, where the tank cycling between aeration on and off
more frequently than desired. Although the controls were designed to provide additional air to the
pilot, the configuration of the valving, in conjunction with the control setpoints, actually limited
how much air could be conveyed to the tanks. Alternatively, the figure shows that beyond the first
two days after increasing aeration capacity the ammonia concentration returned to normal levels,
and thus the extra aeration was no longer needed. Aerobic tank #3, however, shows more days
where the increased aeration capacity was used.
0
2
4
6
8
10
12
14
0
10
20
30
40
50
60
70
80
90
100
11/1
11/2
11/3
11/4
11/5
11/6
11/7
11/8
11/9
11/1
0
11/1
1
11/1
2
11/1
3
11/1
4
11/1
5
11/1
6
11/1
7
11/1
8
11/1
9
11/2
0
11/2
1
11/2
2
11/2
3
11/2
4
11/2
5
11/2
6
11/2
7
11/2
8
11/2
9
11/3
0
NH
3-N
(m
g/L
)
Lb
s A
ir/D
ay @
Std
Co
nd
itio
ns
Aerobic 2 Maximum Allowable Input Daily Avg NH3
39
Figure 3.5.4 December 2017 pilot aeration capacity usage per day
During December, three notable changes were made to the pilot. Most importantly, the ammonia-
based controls were put into effect on December 12th. The initial configuration, as previously
outlined, targeted an ammonia setpoint of 3 mg/L and a high DO setpoint of 1.0 mg/L. To
accommodate for the ability to achieve a high DO setpoint, on December 12th the airflow rates
were increased at aerobic tank 2 and 3 by opening the valves from 0.7 to 1.1 SCFM and 0.3 to 0.5
SCFM, respectively. This is shown in Figure 3.5.4 by the increase in the maximum allowable input
line to approximately 120 pounds of air per day at standard conditions for aerobic tank 2 and to 54
pounds of air per day at standard conditions for aerobic tank 3. On December 13th, the aerobic 3
airflow was again increased from 0.5 to 0.8 SCFM. Following successful ammonia removal to the
3 mg/L threshold, on December 21st, the ammonia setpoint was reduced to 1 mg-N/L.
0
2
4
6
8
10
12
14
0
20
40
60
80
100
120
140
12/1
12/2
12/3
12/4
12/5
12/6
12/7
12/8
12/9
12/1
0
12/1
1
12/1
2
12/1
3
12/1
4
12/1
5
12/1
6
12/1
7
12/1
8
12/1
9
12/2
0
12/2
1
12/2
2
12/2
3
12/2
4
12/2
5
12/2
6
12/2
7
12/2
8
12/2
9
12/3
0
12/3
1
NH
3-N
(m
g/L
)
Lb
s A
ir/D
ay @
Std
Co
nd
itio
ns
Aerobic 2 Aerobic 3 Aerobic 2 Max Aerobic 3 Max Daily Avg NH3
40
Figure 3.5.5 January 2018 pilot aeration capacity usage per day
During the month of January 2018, two process changes occurred. On January 8th, the aerobic 3
tank flow meter was reduced from 0.5 to 0.3 SCFM. This change is apparent in the figure as the
aerobic 3 max line decreases from 54 to 32 pounds of air per day at standard conditions. This is
important to note as the reduction was aimed at not over-aerating when demand was diminished
by the third aerobic zone. In addition, the high DO setpoint was increased from 1.0 mg/L to 1.5
mg/L on January 20th due to a duration of the month operating with a residual ammonia
concentration greater than desired.
During December, prior to implementation of the ammonia-based controls, the aeration capacity
utilized was approximately 99% per day. From December 12th through the end of the month, the
0
2
4
6
8
10
12
14
0
20
40
60
80
100
120
140
1/1
1/2
1/3
1/4
1/5
1/6
1/7
1/8
1/9
1/1
0
1/1
1
1/1
2
1/1
3
1/1
4
1/1
5
1/1
6
1/1
7
1/1
8
1/1
9
1/2
0
1/2
1
1/2
2
1/2
3
1/2
4
1/2
5
1/2
6
1/2
7
1/2
8
1/2
9
1/3
0
1/3
1
NH
3-N
(m
g/L
)
Lb
s A
ir/D
ay @
Std
Co
nd
itio
ns
Aerobic 2 Aerobic 3 Aerobic 2 Max Aerobic 3 Max Daily Avg NH3
41
capacity utilized decreased to an average of 63% per day. Similarly, through the month of January,
the percentage of aeration capacity utilized per day averaged 67%. Through implementation of the
ammonia-based control strategy, the relative aeration capacity utilization percentage decreased,
thus operations were more intermittent than the previous operations in low DO mode. Based on
the figures presented, it is apparent that the allowable input to the aerobic zones was too high for
steady aeration to occur. Because the air flow rates were manually set based on a rotameter at each
aeration drop leg, the increase in flow rate also increased the air flow velocity entering each tank.
As air was allowed to enter at an increased flowrate and speed, the target DO setpoint was achieved
quickly, and often surpassed which was verified by spot checking with the handheld probes. Until
the excess DO was utilized, the solenoid would remain closed and the cycle would continue. This
is further confirmed looking at data from February and March, when manual override of the
controls system left the pilot operating in a high DO mode continuously, due to ammonia probe
issues. Figures 3.5.6 and 3.5.7 provide the capacity analysis for months in which low DO
operations were not utilized.
42
Figure 3.5.6 February 2018 pilot aeration capacity usage per day
It was during February 2018 when an electrode on the ammonia probe began to fail and the data
became inaccurate. This is shown as the daily average ammonia concentration gradually decreases
to essentially 0 mg-N/L. Due to this, the ammonia-based controls failed, by operating in a low DO
mode only, even though the residual ammonia in the mixed liquor was spot checked and exceeded
10 mg-N/L.
0
1
2
3
4
5
6
7
0
20
40
60
80
100
120
140
2/1 2/3 2/5 2/7 2/9 2/11 2/13 2/15 2/17 2/19 2/21 2/23 2/25 2/27
NH
3-N
(m
g/L
)
Lb
s A
ir/D
ay @
Std
Co
nd
itio
ns
Aerobic 2 Maximum Allowable Input Daily Avg NH3
43
Figure 3.5.7 March 2018 pilot aeration capacity usage per day
During March 2018, the ammonia probe was being serviced and tested in adjacent tankage,
separate from the UCT pilot. Thus, the month operated entirely in a high DO mode, which ranged
from 1 mg/L from March 1st until March 22nd, at which time the setpoint was increased to 1.5 mg/L
due to high effluent ammonia in the effluent grab samples. From the results of this analysis, the
allowable inputs to the aeration tanks could be decreased so that the relative capacity usage
increases. Although counterintuitive, a decrease in flow rate would allow the pilot to operate with
the air solenoid valve in the on position for longer durations. The governing equation for fluid
conveyance in relationship to flow and velocity is provided as Equation 10. Where Q is the flow
rate of the fluid being conveyed, V is the velocity, and A is the area of the pipe in which the fluid
is traveling.
Equation 10:
𝑄 = 𝑉𝐴
0
20
40
60
80
100
120
140
3/1
3/2
3/3
3/4
3/5
3/6
3/7
3/8
3/9
3/1
0
3/1
1
3/1
2
3/1
3
3/1
4
3/1
5
3/1
6
3/1
7
3/1
8
3/1
9
3/2
0
3/2
1
3/2
2
3/2
3
3/2
4
3/2
5
3/2
6
3/2
7
3/2
8
3/2
9
3/3
0
3/3
1
Lb
s A
ir/D
ay @
Std
Co
nd
itio
ns
Aerobic 2 Maximum Allowable Input
44
Because the flow rates at the droplegs to the diffusers were increased, but the tubing in which the
air was conveyed was not, the velocity of the air entering the tanks through the diffusers increased.
The increase in velocity enabled the air to rapidly enter the system and quickly reach the high DO
setpoint established in the ammonia-based aeration controls. This resulted in the underutilization
of the full capacity of the aeration process, as shown in Figures 3.5.4 to 3.5.7. In order to operate
the system in a manor such that more air is allowed to be introduced, either the flow rate has to be
decreased, or the cross sectional area of the tubing must be increased. The operational strategy
neglected to consider effects of velocity of the air entering the aerobic tankage which created even
more of an intermittent aeration effect than prior months. By allowing the process to operate closer
to 100% capacity usage, more air will be able to enter the system over a longer period of time and
the pilot will operate closer to a completely mixed, and continuously aerated aeration basin, as full
scale operations do.
3.6 Effects of Ammonia-Based Aeration Controls – Aeration Limitation
According to the stoichiometric equations governing oxidation of BOD and ammonia, a total of
5.7 pounds (2.6 kg) of oxygen is required for the removal of BOD (1.1 pounds) and oxidation of
ammonia to nitrate(4.6 pounds)1. Equation 11 shows the total oxidation reaction of ammonia to
nitrate.
Equation 11:
𝑁𝐻4+ + 2𝑂2 → 𝑁𝑂3
− + 2𝐻+ + 𝐻2𝑂
Utilizing the same aeration duration data as presented in the aeration capacity results and
discussion section and the influent loadings presented in Section 3.1, further analysis was
developed to totalize and compare the oxygen added to the aerobic zone against the oxygen
45
required for nutrient removal. An oxygen deficiency is present when the oxygen provided to the
system is lower that what is required to theoretically oxidize all of the BOD and ammonia entering
the system. The influent loadings were known and BOD loading was added to the influent
ammonia loading to totalize the pounds of nutrients needed to be oxidized. Using the
stoichiometric ratios, a factor of 5.7 was applied to the influent loading sum to generate a
theoretical oxygen requirement for complete oxidation. This is summarized in Equation 12.
Equation 12:
𝑂𝑥𝑦𝑔𝑒𝑛 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 (𝑙𝑏𝑠
𝑑𝑎𝑦) = 5.7 ∗ (𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡 𝐵𝑂𝐷 (
𝑙𝑏𝑠
𝑑𝑎𝑦) + 𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡 𝑁𝐻3 (
𝑙𝑏𝑠
𝑑𝑎𝑦))
Although influent conditions were well known, numerous assumptions were utilized in regards to
the diffused aeration system. It is known that the diffusers were located 4 feet (1.2 meters) below
the water surface, but based on the age and condition of the membranes, the standard oxygen
transfer efficiency (OTE) was assumed to be 20%. Manufacturer literature commonly expresses
these OTEs based on a submergence of 15 feet (4.5 meters), and thus even the 20% assumed OTE
is likely to be much higher than what occurred under the pilot conditions with shallow depths to
the diffuser and the quality of the membrane. Nonetheless, a 20% OTE was used for the calculation
of oxygen deficiency and upcoming analysis. Oxygen added was calculated by Equation 8 and a
total sum for the oxygen delivered across all three aerobic tanks was used. Oxygen required was
calculated using Equation 12. Thus, Equation 13 shows the calculation used for determination of
daily oxygen deficiency during pilot operations. Any results of the deficiency calculation below
zero indicate that even with a notably higher OTE than anticipated, the oxygen delivery to the
system is not enough to provide complete oxidation, and thus removal, of BOD5 and ammonia
from the waste stream.
46
Equation 13:
𝑂𝑥𝑦𝑔𝑒𝑛 𝐷𝑒𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 (𝑙𝑏𝑠
𝑑𝑎𝑦)
= (𝑂𝑥𝑦𝑔𝑒𝑛 𝐴𝑑𝑑𝑒𝑑 (𝑙𝑏𝑠
𝑑𝑎𝑦) ∗ 𝑂𝑇𝐸 (%)) − 𝑂𝑥𝑦𝑔𝑒𝑛 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑(
𝑙𝑏𝑠
𝑑𝑎𝑦)
Figure 3.6.1 depicts the oxygen deficiency, in pounds per day, based on the influent loading to the
pilot and the oxygen assumed to be delivered across the three aerobic zones. The figure shows that
oxygen deficiency was approximately between 5 and 10 pounds per day (2.3 to 4.5 kilograms per
day), however it is again reiterated that due to the shallow depths to the diffusers, the transfer
efficiencies are likely much lower than shown here. Further considerations and evaluation would
be required to identify the exact OTE within the pilot, as it is known that both depth of diffuser
and air flow rate through the diffuser have effects on the OTE. With an increase in diffuser
submergence, OTE increases which would reduce the oxygen deficiency effects. Additionally,
with increased flow rates, which occurred during the ammonia-based controls phase of operation,
air bubbles through the diffuser are larger which reduces surface area and OTE, as compared to
lower flow rates13. This assumption also shows the few instances of oxygen surplus as a very
conservative value, whereas the surplus was likely much lower for those select days. The data,
which starts September 12th, 2017, shows few instances where a surplus of oxygen was present
within the totalized aerobic volume of 420 gallons.
47
Figure 3.6.1 Oxygen deficiency analysis within the pilot aerobic zone
In addition to the daily summary of oxygen deficiency, a totalized mass per month was compiled
and is presented in Table 3.6.1. During the seasonal transition, as temperatures decreased and
influent loadings increased, the oxygen deficiency to the pilot increased. It should be noted that
February 2018 includes only data through the 12th of the month.
Table 3.6.1 Monthly totals of oxygen deficiency within the pilot aerobic zone
Month - Year Oxygen Deficiency (lbs/month) Oxygen Deficiency (kg/month)
Sep-17 -7.4 -3.4
Oct-17 -45.4 -20.6
Nov-17 -79.9 -36.2
Dec-17 -107.5 -48.8
Jan-18 -172.2 -78.1
Feb-18 -33.9 -15.4
(15)
(10)
(5)
0
5
10
15
20
25
30O
xygen
Def
icie
ncy
(lb
s/d
ay)
&
NH
3-N
(m
g/L
)
Oxygen Deficiency NH3
48
The aeration limitation during the ammonia based aeration controls phase of operation is clearly
present and indicates that the physical configuration of the pilot, in conjunction with the controls,
led to a shortage in oxygen delivery to the aerobic treatment zones.
3.7 Effects of Ammonia-Based Aeration Controls – Exceedance Evaluation
As one of the main goals of adding enhanced aeration controls to the pilot was to successfully
remove ammonia year round, historical effluent ammonia results were compiled and compared
across the operational phases. Using a generic exceedance evaluation with a scale in increments
of 4 mg/L, Figures 3.7.1 and 3.7.2 were developed to represent the number of exceedances of each
concentration and denote the season in which they occurred.
Figure 3.7.1 Effluent ammonia exceedance counts for 2017 operation
During 2017 a total of 37 exceedances occurred, 81% of which were greater than 4 mg-N/L but
less than 8 mg-N/L. 2 of the 30 exceedances of 4 mg-N/L can be directly attributed to a pilot
operation issue; whereas one sample was taken following a period where the wasting pump was
left on for over 24 hours and another was taken following a loss of biomass due to a transfer line
0
10
20
30
40
20 16 12 8 4
Co
unt
Concentration (mg/L)
Summer Winter
49
break. Only 6 exceedance counts were present during the summer months, defined as May through
September. The other 31 instances occurred during October through April, when water
temperatures have decreased.
Figure 3.7.2 Effluent ammonia exceedance counts for 2018 operation
2018 operational evaluation ended with a sample taken March 28th, thus all exceedance counts fall
within the previously defined winter period. A total of 47 exceedances were present in the grab
sample results analysis, with just 40% of those falling between 4 mg-N/L, but less than 8 mg-N/L.
In a span of 3 months, the total exceedance count of 2018 exceeded the entire year of 2017. As
outlined from previous sections, a number of factors compounded to result in decreased
performance during the 2018 operation supplemented with ammonia-based controls. However, the
pilot was provided with additional air during the 2018 operation so it is likely that the exceedance
counts would be even higher had the low DO operation been maintained with the increasing
influent loads and low water temperatures.
0
5
10
15
20
20 16 12 8 4
Concentration (mg/L)
50
3.8 Simultaneous Nitrification and Denitrification
With low DO and intermittent aeration process control used prior to implementing ammonia-based
controls, conditions were favorable for both nitrifying bacteria and heterotrophic denitrifying
bacteria. By providing low concentrations of dissolved oxygen, the low DO nitrifying bacteria had
been acclimated and the denitrifying bacteria were able to survive and grow, which is suppressed
or eliminated at higher DO conditions. By increasing aeration associated with ammonia-based
controls it is anticipated that little to no denitrification could occur and thus SND would decrease.
Based on Equation 5, SND calculations were performed and compiled to determine when more
simultaneous removal of nitrogenous species occurred. Figure 3.8.1 below shows daily SND
calculations compiled since the UCT conversion in June 2016.
Figure 3.8.1 SND calculation summary for the pilot operated as UCT
The winter of 2016 includes numerous negative values for SND, indicating an accumulation of
nitrite and nitrate, and thus little to no denitrification occurring in the process. The accumulation
of NOx during the winter of 2016 may be potentially described as a product of limited carbon
-4
-2
0
2
4
6
8
10
12
14
Jun-16 Aug-16 Oct-16 Dec-16 Feb-17 Apr-17 Aug-17 Nov-17
SN
D (
mg N
/L)
51
availability for denitrification, due to the successful nutrient removal as previously shown on
Figure 3.2.1. The increase in effluent NOx across the aerobic tanks indicates ammonia removal,
however this increases the effluent TN concentration which may be of concern with upcoming
future permit terms. Conversely, the SND calculations have yielded positive values through the
ammonia-based controls phase indicating a reduction in ammonia across the aerobic zone, and less
NOx accumulation than ammonia reduction. The increasing trend in SND is significant in that
total nitrogen removal, even with the increased DO through the winter of 2018, may be possible
with the UCT configuration. However, the lack of NOx in the system during ammonia-based
controls testing, does not tell the whole story. The results of monthly average NOx and NH3 show
that the decrease in nitrates and nitrites in the pilot were not caused by SND, but by the lack of
nitrification during these months as shown in Figure 3.8.2.
Figure 3.8.2 Effluent NOx and NH3 concentrations for the pilot operated as UCT
0
2
4
6
8
10
12
14
Co
nce
ntr
atio
n (
mg/L
)
NOx NH3
52
The decrease in nitrate and nitrate concentrations through the duration of the pilot, and especially
during the winter of 2018, indicate unsuccessful nitrification of the ammonia. Thus, the increases
in SND, with increasing aeration, is not entirely reliable. One potential cause of the increase in
SND is related back to Section 3.5 and the decreased utilization of the full aeration capacity. The
intermittent operation as configured through the experiment of the controls, limited aeration which
lead to increased ammonia in the effluent thus yielding less NOx and promoted operations which
were nearly aerated in batches, as opposed to continuous aeration. The efficiency of SND in a
sequencing batch reactor with similar influent wastewater characteristics was shown to increase as
dissolved oxygen decreased, from 51% efficient at 2.5 mg/L DO to 98% efficient at 0.5 mg/L DO7.
It is likely that if the pilot is to be operated in more of a continuous aeration mode and that oxygen
deficiency is not present, the ammonia-based controls will decrease the SND and NOx in the
effluent would increase. Total nitrogen in the effluent could presumably stay low, if all of the
ammonia is oxidized when oxygen is delivered in excess. An additional consideration that may
result in the increase in SND rates during the ammonia-based controls operation phase is that due
to decreased reactor performance, residual carbon sources increased in addition to ammonia. By
leaving excess carbon in the system, heterotrophic denitrifying bacteria are more apt to reduce
nitrate to nitrogen gas. Furthermore, internal recycle rates have been tied to SND and may be a
way to control effluent total nitrogen. That is, as internal recycles are introduced to the process, as
the pilot had, SND rates and efficiency increased compared to processes without14. As the pilot
became saturated with ammonia and nitrates in the RAS stream during the cold water temperature
months, the internal recycle further aided in SND by distributing the nitrates to a carbon rich
anaerobic environment, suitable for denitrification. It may be that as performance decreased
through the winter, the oversaturation of nutrients resulted in increased SND rates and activity.
53
3.9 Nutrient Profiles
As described in Section 2.4, nutrient profile samples were taken from influent, across all process
tankage, to effluent. The analysis of this data provided insight related to differences in performance
during ammonia-based control against low DO control during summer and winter seasons. By
compiling a monthly average of all nutrient sampling data, trends in the removal of ammonia and
total nitrogen, as well as the generation of NOx, can be compared across time. Figures 3.9.1, 3.9.2,
3.9.3, 3.9.4, and 3.9.5 provide the monthly average profile results from July 2017 to December
2017 for total nitrogen, ammonia, and NOx.
Figure 3.9.1 Monthly average nutrient profile sampling results for July, 2017
0
5
10
15
20
25
30
35
40
Infl Ana 1 Ana 2 Ana 3 Anox Aer 1 Aer 2 Aer 3 Effl
Co
nce
ntr
atio
n (
mg/L
)
NH3 NOx Total N
54
Figure 3.9.2 Monthly average nutrient profile sampling results for August, 2017
Figure 3.9.3 Monthly average nutrient profile sampling results for September, 2017
0
5
10
15
20
25
30
35
40
Infl Ana 1 Ana 2 Ana 3 Anox Aer 1 Aer 2 Aer 3 Effl
Co
nce
ntr
atio
n (
mg/L
)
NH3 NOx Total N
0
5
10
15
20
25
30
35
40
45
Infl Ana 1 Ana 2 Ana 3 Anox Aer 1 Aer 2 Aer 3 Effl
Co
nce
ntr
atio
n (
mg/L
)
NH3 NOx Total N
55
Figure 3.9.4 Monthly average nutrient profile sampling results for October, 2017
Figure 3.9.5 Monthly average nutrient profile sampling results for November, 2017
The profiling results, as well as the influent results, show a continuously increasing load entering
the pilot, but a generally stable removal of ammonia. Additionally, ammonia removal was
0
5
10
15
20
25
30
35
40
45
Infl Ana 1 Ana 2 Ana 3 Anox Aer 1 Aer 2 Aer 3 Effl
Co
nce
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n (
mg/L
)
NH3 NOx Total N
0
10
20
30
40
50
60
Infl Ana 1 Ana 2 Ana 3 Anox Aer 1 Aer 2 Aer 3 Effl
Co
nce
ntr
atio
n (
mg/L
)
NH3 NOx Total N
56
substantially noticed by aerobic tank 2. For the duration of operation leading up to the ammonia-
based controls, minimal oxidation of ammonia occurred between aerobic tank 2 and the results of
the effluent sample. The months of December 2017, January, and February 2018 are summarized
and presented in Figures 3.9.6, 3.9.7, and 3.9.8. It should be noted that due to laboratory equipment
related issues during the month of January 2018, no nitrate nor nitrite data was collected for
compiling NOx production.
Figure 3.9.6 Monthly average nutrient profile sampling results for December, 2017
0
5
10
15
20
25
30
35
40
45
Infl Ana 1 Ana 2 Ana 3 Anox Aer 1 Aer 2 Aer 3 Effl
Co
nce
ntr
atio
n (
mg/L
)
NH3 NOx Total N
57
Figure 3.9.7 Monthly average nutrient profile sampling results for January, 2018
Figure 3.9.8 Monthly average nutrient profile sampling results for February, 2018
Based on profile results during the operational phase utilizing ammonia-based control, influent
loadings continued to increase and the entire aerobic capacity was utilized for treatment. Whereas
0
5
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20
25
30
35
40
45
Infl Ana 1 Ana 2 Ana 3 Anox Aer 1 Aer 2 Aer 3 Effl
Co
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mg/L
)
NH3 Total N
0
10
20
30
40
50
60
Infl Ana 1 Ana 2 Ana 3 Anox Aer 1 Aer 2 Aer 3 Effl
Co
nce
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n (
mg/L
)
NH3 NOx Total N
58
prior to the December through February profiles aerobic tank 3 provided little additional treatment,
the results show this additional treatment capacity was critical during the coldest months.
Using the profile data from the anoxic stage to the effluent, nutrient consumption rates were
calculated to compare the treatment efficiency of the pilot across each month. By evaluating the
difference in concentration from the anoxic tank to the effluent sample and normalizing the
removal with the volatile solids concentration across the basins, a nutrient consumption rate
expressed as concentration over mass of volatile solids (mg/L*g VSS) was calculated. Figure 3.9.9
below shows the results of this analysis for ammonia consumption as well as total nitrogen
consumption. Through the month of April to the fall of 2017, consumption rates of ammonia were
relatively high due to warm water temperatures and thus more efficient oxidation of ammonia. The
months of December and January begin to show a decrease in the ammonia consumption rates,
directly related to the drop in temperatures previously discussed in Section 3.3. The month of
December also was the start of the ammonia-based controls which enabled operations cycle
between high and low DO modes. Indicated by the increases in ammonia consumption rate over
February 2018, the additional dissolved oxygen provided by the control strategy appears to have
caused an increase in the ammonia consumption rates.
59
Figure 3.9.9 Monthly average consumption rates from the anoxic zone to the pilot effluent
In general, the total nitrogen consumption rates followed the ammonia consumption rate trends
except for the transitional period between warm and cold water conditions (September to
December). As ammonia consumption rates were generally trending downward, with the exception
of the peak in November, total nitrogen consumption rates were steadily increasing. Thus, the total
nitrogen consumption rates shown as increasing are likely due to the decline in NOx production
caused by reduced oxidation of ammonia over this time. Nonetheless, these results indicate that by
increasing the dissolved oxygen concentration in the pilot during periods of cold weather with
ammonia-based controls, the ammonia consumption rates increased. However, due to a limited
HRT and the increasing influent loads, effluent concentrations were not suppressed to satisfactory
concentrations.
0.0000
0.0005
0.0010
0.0015
0.0020
0.0025
0.0030
0.0035C
onsu
mp
tio
n R
ate
(mg/L
*gV
SS
)
NH3-N TN
60
3.10 Clarifier Considerations
The separation of clear water and biomass following the aeration process is accomplished through
sedimentation or clarification. One final clarifier on the pilot scale reactor collected mixed liquor
and settled biomass to be returned to the anoxic tank. A gauge of clarifier effectiveness is the
sludge volume index which indicates the settling characteristics of the sludge. The literature states
that SVI values around 100 mL/g are indicative of good settling sludge, and that values at or
exceeding 150 mL/g are associated with filamentous organisms and poor settling sludge1. Based
on approximately 12 settling tests and TSS measurements per month, Table 3.10.1 below outlines
the monthly average SVI values from July 2017 through February 2018, which routinely exceeded
200 mL/g. A historical summary of the SVI for the pilot is provided as a supplementary table.
Table 3.10.1 Monthly average SVI summaries for two settling test containers
Month - Year SVI - Plastic Cylinder SVI - Glass Beaker
July-17 255 -
August-17 232 218
September-17 250 189
October-17 206 191
November-17 245 211
December-17 271 245
January-18 251 233
February-18 266 266
Average 245 218
Historically, one settling test was performed on a routine basis with a 1,000 mL plastic cylinder
which had a small diameter. As a supplement and to try and better replicate a standard settleability
test, a trial of 7 months also utilized a 1,000 mL glass beaker with a larger diameter. Due to the
friction losses associated with the narrow cylinder, readings for the settling test were always
61
greater. Still, when the two settling test containers were utilized, the SVI showed minimal
improvement. In evaluating the sludge settling characteristics, it is clear that the SVI for the pilot
far exceeds what is typically classified as good settling sludge. Because of this, additional
considerations would need to be made related to clarifier capacity and/or design of additional
clarifiers for a full scale implementation. With poor settling sludge, the opportunity for losing
biomass in the effluent is enhanced which creates potential effluent TSS violations and is a loss of
microbes from the system that are vital to the nutrient removal process.
In addition to noting the high SVI associated with the pilot, an increasing trend was also seen when
comparing late 2016 to February 2018, when additional air was added due to the ammonia-based
controls. Figure 3.10.1 shows the upward trend over time associated with the pilot biomass SVI.
Although low DO conditions are prone to high SVI values and filamentous growth, increased DO
conditions within the pilot seem to decrease the sludge settleability further.
Figure 3.10.1 Monthly average SVI trending across low DO operation and ammonia-based control implementation
As the increase in SVI is noticed with increased DO in the pilot, it should be noted that this directly
conflicts the results from an SVI evaluation in Colorado Springs, CO, where increased dissolved
0
50
100
150
200
250
300
SV
I (m
L/g
)
SVI - Plastic SVI - Glass
62
oxygen was directly related to low SVI values and declining DO resulted in high SVIs. At the
Colorado Springs WWTP, dips in DO below 2 mg/L caused high SVI results11. Ultimately, it will
be important to evaluate the clarifier capacity moving forward. It appears that the microbial
community acclimated to low DO conditions, which was then introduced to increased aeration,
acts differently than conventional activated sludge communities from full scale plant studies.
Furthermore, operating WWTPs at high SVIs reduces the capacity of the secondary clarification
process which simultaneously reduces the capacity of the plant and risks washout12.
63
CHAPTER 4: RECOMMENDATIONS
4.1 Sampling Methods
The process of sampling for both influent and effluent conditions associated with the pilot were
considered grab samples. Although this methodology allows for simple collections independent of
a set schedule, it introduces errors as noted in Section 3.3. By employing a composite sampler to
the pilot, a full 24 hour history of the operation is captured for analysis. Composite samplers can
be automated to collect sample volumes based on time of day and flow pacing, while also operating
only on specified days of the week. By collecting small volume samples and accumulating those
in a common collection tank across a day, peaks and valleys in the process performance are
accumulated and decisions can be based on a representative sample. An additional composite
sampler options allows for samples taken and collected in individual bottles on a rotating rack
within the refrigerated containment of the sampler. This would allow for individual sample
analysis before combining the results for a 24 hour composite sample. As shown with the
variability in ammonia concentrations within the aerobic mixed liquor during the pilot operations,
a single grab sample of the effluent is not indicative of the entire day, but has been historically
analyzed as such with the pilot. The implementation of a composite sampler would serve as a
useful investment such that the entire story becomes captured, opposed to the discrete time point
associated with the historical method of collecting grab samples.
On the other hand, TSS sampling is one area of the process that is traditionally performed with the
simple grab samples. Due to the completely mixed environments and large values often associated
with MLSS, it is less critical to see the small daily variations. Continuing to collect TSS samples
as grab samples follows conventional operations and should be continued.
64
4.2 Hydraulic Residence Time
The HRT of the pilot was fixed due to a constant flow rate from the influent feed pump and the
tankage present and in use at the pilot. The setup of the pilot achieved an HRT, within the anoxic
and aerobic treatment zones, of approximately 7.7 hours, whereas NSWWTP reports operating
near 12 hours through the secondary treatment process. By adding an additional, equally sized
(105 gallons), aerobic tank to the process the HRT would be increased to slightly less than 10
hours. Although this would require an additional diffuser and aeration drop pipe, the added
residence time provides the nitrifying bacteria more opportunity to oxidize ammonia. With a
second additional aerobic zone, thus totaling 630 gallons, the secondary treatment HRT would be
approximately 11.6 hours. By better replicating the full scale operations, influent loadings effects
on the pilot can provide insight as to how full scale would perform. The current configuration of
the pilot left the treatment process stressed with no safety factor in treatment because of the
shortened residence time. Based on the ammonia consumption rates summarized in Section 3.9,
with the increased DO conditions and cold water temperatures, approximately 2 mg/L*hr can be
consumed. By increasing HRT to the pilot in the form of one or two additional aerobic tanks
(105 gallons each), ammonia could potentially be reduced by 3.9 mg/L or 7.8 mg/L, respectively.
Although reducing pump speed to achieve additional HRT is a simpler option, it is likely that
line clogging frequency would increase further with the decrease in flow velocities this would
create. This additional ammonia reduction through increasing the HRT could provide enough
treatment capacity to further optimize the pilot and potentially pass an entire winter season
without ammonia effluent quality concerns.
65
4.3 Solids Residence Time
Wasting rates controlled the SRT to 10-12 days through the duration of the pilot research. By
increasing the SRT and thus accumulating more biomass in the aerobic zones of the pilot, the
potential for increased nutrient removal exists. Typical wasting rates from 24 to 48 gallons per day
were utilized during the pilot research. By reducing the volume of solids wasted on a daily basis,
the potential for accumulation of more nitrifying bacteria exists. Conversely, too large of an
increase in the SRT can promote conditions for growth of higher organisms and create a potentially
detrimental side effect. Another aspect of the SRT discussion revolves around including clarifier
scum solids, which was not done as a part of this research. Preliminary approximations based on
TSS grab samples of the scum removed from the clarifier and the volume of scum removed show
that including the solids removed in the clarifier scum stream, about a 28% reduction in SRT is
observed, or approximately 3 days. Based on these calculations, dating from November 2017 to
February 2018, it may be of interest to consider biomass removed from the system in the clarifier
scum. While a 10 to 12 day SRT was generally targeted, scum removal considerations reduced this
to a 7 to 11 day SRT, based on the TSS of the grab sample and the quantity of scum removed as a
part of the daily maintenance schedule. Thus although the SRT control was generally dictated
exclusively by sludge wasting flow rates, it may be of interest to continue to compare the effects
of scum removal for future research.
Conversely, this approach will likely increase the MLSS in the aerobic tanks. Based on historical
operation and comparison to the full scale NSWWTP operations, pilot MLSS were already quite
high and by increasing the SRT further, issues with high MLSS may develop. Table 4.3.1 below
summarizes the monthly average MLSS concentrations, taken from aerobic tank 2, since July
66
2017. A historical monthly summary since the start of the pilot in 2014 is provided in the
supplementary tables section.
Table 4.3.1 Historical MLSS concentrations from pilot aerobic tank 2
Month - Year MLSS (mg/L)
Jul-17 3635
Aug-17 3753
Sep-17 2983
Oct-17 3388
Nov-17 3524
Dec-17 3286
Jan-18 3744
Feb-18 3596
Average 3506
The mixed liquor concentrations within the pilot are generally considered to be exceeding, or near
exceeding, the limits for conventional activated sludge treatment and fall more in the ranges of
extended aeration operation, like treatment with an oxidation ditch1. If scum totals begin to be
incorporated with the SRT calculations, caution should be taken in the event that MLSS
concentrations increase even further.
4.4 Probe Usage
From the first attempt at implementing ammonia-based controls on a low DO pilot, it became clear
that the most important aspect of the process was the reliability of the ammonia probe. Probe
malfunctions began in the month of February which limited the overall duration of experimenting
with the controls. However, moving forward it is recommended to ensure a cleaning frequency of
at least 4 days per week. The maintenance schedule utilized a 4 day per week cleaning cycle which
should be continued as a minimum, especially if mixing in the final aerobic tank is not sufficient.
When airflow to the final aerobic tank, where the ammonia probe was located, was reduced the
67
development of biofilms were more apt to foul the probe. Until user intervention occurred,
ammonia readings could be altered by the presence of the biomass on the electrodes. Additionally,
the YSI user manual calls to place the sensor in a maintenance condition each time the sensor was
taken out of the water. By ensuring this condition is switched on for each cleaning, unwanted
reactions of linked outputs can be avoid and the integrity of the probe outputs is maintained.
Ultimately, based on usage at the pilot and recommendations within the operations and
maintenance manual from the probe manufacturer, it is advised to continue cleaning the probe a
minimum of 4 days per week, and ensuring the maintenance condition mode is switched on for
each cleaning.
The other aspect of the ammonia probe reliability is related to the calibration process. Since the
AmmoLyt probe relies on a single point calibration, it would be useful to add a calibration schedule
to the routine maintenance schedule. In conjunction with a calibration schedule, additional
ammonia sampling could verify the accuracy of the probe readout. By collecting a filtered sample
of the mixed liquor near the probe and recording the probe readout at that time, sample results can
be compared and used to assess the validity of the probe for that given time period. Since the
ammonia data is so vital to the process, the actions of cleaning the probe and confirming the outputs
are crucial to the overall success of the pilot operation.
4.5 Intermittent Aeration
As was shown through the aeration capacity utilization analysis, the first iteration of ammonia-
based controls operated in a more intermittent fashion than the low DO operations. To better
simulate a full scale operation, where the cycling of blowers on and off is detrimental to the
longevity of the equipment, the pilot air flow meters should be reduced so that a lower flowrate
into the aerobic zone reduces air velocity entering the tank and thus limits the response time to
68
achieving the high DO setpoint, governed by Equation 10 as previously described. By restricting
the flow to which air is introduced to the pilot, it is reasonable to assume that the aeration
solenoid valve will be open longer which limits the intermittent aeration scheme. It is
recommended that for future work with the pilot that more attention be paid to the flowrates in
which air is added to the tankage. Presumably, from Figures 3.5.4 and 3.5.5, 120 pounds of air
per day at standard conditions as a maximum allowable input is greater than needed to achieve
the desired DO. At this mass flow rate, the air flow meters were set at 1.1 SCFM. To allow
approximately 97 pounds of air per day into aerobic tank 2, the flowmeter should be set at 0.9
SCFM. An increase to 1.0 SCFM would enable a maximum mass flow rate of 108 pounds per
day. In conjunction with the changes to air flow to aerobic 2, the adjacent tankage should also be
addressed. In aerobic tank 1, the flow rate was fixed for the duration of the ammonia-based
controls at 1.5 SCFM which allowed a maximum of 162 pounds of air per day into the tank.
Upon implementation of the controls, the maximum amount utilized was approximately 136
pounds per day. By reducing the aerobic 1 flowmeter valve to 1.3 SCFM, approximately 140
pounds per day would be the maximum allowable input. Finally, tank 3 operated between 0.3
and 0.5 SCFM during the ammonia-based controls trial period, allowing between 33 and 54
pounds of air per day into the tank. Because this tank housed the ammonia probe and is operated
at the lowest DO conditions, a complete mixed environment is important to maintain solids in
suspension and to achieve reliable probe results. To do so, it would be recommended to operate
at 0.4 SCFM, yielding a maximum of approximately 44 pounds of air per day. The most air that
was called for during the ammonia-based controls period was approximately 37. To summarize
the recommendations for future manual air flow rate controls, see Table 4.5.1 below. However, if
69
HRT is not adjusted (see above), this may still not be sufficient to guarantee efficient nitrification
with the observed higher loadings and lower temperatures.
Table 4.5.1 Summary of fixed airflow meter conditions and recommendations
Aeration Configuration Aerobic 1 Aerobic 2 Aerobic 3
Previous flowrate (SCFM) 1.5 1.1 0.3 to 0.5
Previous mass flow rate (lbs air/day @ STD
Conditions) 162 97 33 to 54
Recommended flowrate (SCFM) 1.3 1.0 0.4
Recommended mass flow rate (lbs air/day @ STD
Conditions) 140 108 44
Based on the previous aeration usage and capacity analysis, the recommended flowrates should
serve as a starting point for future pilot work. These setpoints are in an attempt to better replicate
full scale processes, where intermittent aeration is not used. The configuration should serve to
provide a more constant aeration scheme, while still achieving a high DO setpoint up to 1.5 mg/L,
and provide sufficient mixing to keep solids in suspension within the aerobic zones. If future work
indicates a higher DO setpoint is desired, it is recommended to monitor the aeration usage
compared to capacity to hone in on the increases required at the airflow valves. It may also be
required to increase the cross sectional area of the diffuser piping, so that velocity through the
conveyance system is reduced. By reducing air velocities, the reaction time to achieving a high
DO setpoint is suppressed which enables more mass of air, and thus oxygen, to enter the system.
4.6 Dissolved Oxygen Tracking
Based on the results presented previously, it may be of benefit to approach the aeration scheme
differently. In the event that the recommendations from section 4.5 do not serve as a solution,
70
instead of capping the aeration based on a DO setpoint, the pilot could be operated to cycle air
only based on ammonia concentration and thus DO is simply monitored only. By allowing the
system to operate with intermittent aeration only based on an ammonia setpoint, air will
continually be fed to the system until the ammonia can be reduced. With the trending capabilities
of the probes, this would indicate a potential high DO setpoint to be targeted based on ammonia
and temperature factors. The results of allowing the system to aerate beyond an operator selected
high DO setpoint would likely allow the pilot to operate with an oxygen surplus, as opposed to the
deficiency highlighted in section 3.5. Then using trending, as was done with the ammonia probe
during this iteration of the controls, a target high DO setpoint can be identified and then decreased
in a stepwise fashion similar to how the low DO community was acclimated.
4.7 Alkalinity Monitoring
An additional sampling and monitoring point to consider for the pilot performance is alkalinity.
As the oxidation of ammonia stoichiometric equation notes, bicarbonate (HCO3-) is consumed to
produce nitrate at a rate of 7.14 grams of alkalinity as calcium carbonate (CaCO3) per gram of
ammonia converted1. This reduction in alkalinity also reduces the pH in the liquid stream. It has
been observed that at a pH less than 6.45 or greater than 8.95 complete inhibition of AOB and
NOB communities’ occur10. By incorporating an alkalinity sample to the pilot maintenance
schedule, it can be assured that nitrification is not being limited by alkalinity, or inhibited by pH.
4.8 Reduction in High Strength Recycle Streams
It is understood that treatment facilities like NSWWTP where solids digestion, thickening, and
dewatering occur, upwards of 20% of the nitrogen load comes from these recycle streams23. The
pilot reactor experienced at least one known instance of slug loading caused by a high ammonia
71
recycle stream from the biosolids dewatering process of centrifugation. There are ongoing research
efforts between NSWWTP and UW-Madison focused on reducing high nutrient recycle streams,
specifically from the Ostara struvite harvester process, which generates a liquid waste stream of
concentrated ammonia where nitrogen concentrations can exceed 200 mg NH4+-N/L4. By focusing
on nutrient reduction efforts upstream of the secondary treatment process, the low DO aerobic
treatment may provide a more stable operation due to the decreased slug loading effects. It is a
worthwhile investment to continue understanding the implications of side-stream liquid treatment
at NSWWTP so as to reduce the dependence on secondary treatment processes to successfully
remove ammonia.
4.9 Monitoring of Process Flows
There are a number of advantageous in monitoring ammonia concentration in real-time, however
it has also exposed the need for full scale process monitoring. Based on Figure 3.3.2 and a seeing
what a single event of centrate loading can do the treatment process, it is recommended that all
events be included in a database for historical trending. It is likely that other events occurred in the
full scale treatment plant, but were not identified as such because of the limitations with the current
system. In addition to monitoring of biosolids processing events, the hauled waste receiving station
is another area of concern. Having an idea of the type of wastes, the volume, and the time the load
arrived would also be of great value when trending shows blips in ammonia removal. Having this
information could potentially rule out isolated events when it may have previously been considered
a biological upset or failure.
72
CHAPTER 5: CONCLUSIONS
• Low DO nutrient removal supplemented with ammonia-based controls can provide
seasonal treatment capability under proper conditions. That is, when water temperatures
exceeded 16 degrees Celsius and the controls were in place, effluent ammonia
concentrations from the pilot averaged below 3 mg/L.
• Ammonia-based aeration controls were shown to provide flexibility and potential energy
savings by cycling between high and low DO conditions based on the loading. However,
further optimization is required to address successful nutrient removal year round.
• The increases in oxygen loading through the implementation of ammonia-based controls
increased the ammonia consumption rates to levels at or above those present during
summer operations. Thus, given sufficient time for nutrient consumption it is apparent that
the effects of temperature on a low DO system may be able to be combated with
optimization of the process.
• Based on seasonal variations in loadings, and increased loadings to NSWWTP during
2018, and subsequently the pilot, providing the required mass of oxygen to the aerobic
zone is critical to effluent quality and reactor performance. By allowing the full aeration
capacity to be utilized and letting the system determine a high DO setpoint, ammonia
removal through decreased temperature seasons can likely be achieved. However,
sufficient hydraulic retention time has to be provided in the aeration tanks as increased DO
will not be sufficient to achieve efficient nitrogen removal if not enough time is provided
to complete nitrification.
• With advances in operational strategies, data monitoring and acquisition, the most
important tool for operators is the technology providing the operational data. The utmost
73
care and attention should be given to all of the probes in a process so that data is reliable
and provides operations as intended.
• Pilot scale results can only be accurately scaled to systems of similar configuration. For a
true representation of the process efficiency, the pilot should be operated as the full scale
would, with similar SRT, HRT, and sampling methods.
74
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2. Martirano, J 2015, ‘Evaluating Biological Nutrient Removal Processes in a Pilot-Scale
Sequencing Batch Reactor Using Low Dissolved Oxygen Aeration’, MS thesis, University of
Wisconsin-Madison, Madison, WI.
3. Keene, N 2015, ‘Toward Energy Positive Wastewater Treatment: Identifying a Strategy to
Achieve Stable and Effective Nutrient Removal with Low Dissolved Oxygen Conditions’, MS
thesis, University of Wisconsin-Madison, Madison, WI.
4. Owen, B 2017, ‘Treating Struvite Harvester Effluent with Partial Nitritation-Anammox
System’, MS thesis, University of Wisconsin-Madison, Madison, WI.
5. Serralta, J. et al. “A Supervisory Control System for Optimising Nitrogen Removal and
Aeration Energy Consumption in Wastewater Treatment Plants.” Water Science and
Technology, vol. 45, no. 4, 2002, pp. 309–316.
6. Keene, Natalie A. et al. “Pilot Plant Demonstration of Stable and Efficient High Rate
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1345., doi:10.1002/jctb.2438.
1
APPENDIX A
Figure S.1 Historical timeline of pilot temperatures and effluent ammonia grab sample results
0
5
10
15
20
25
30
35
0
5
10
15
20
25
30
September-14 March-15 October-15 April-16 November-16 May-17 December-17
Wat
er T
emp
(C
)
Eff
luen
t N
H3
(m
g/L
)
2
Table S.1 Monthly average influent concentrations for various constituents in the pilot feed stream
Month - Year BOD5 (mg/L) NH3 (mg/L) Organic N (mg/L) TKN (mg/L) TP (mg/L)
Apr-16 173 30 13 43 7.3
May-16 191 32 12 44 7.5
Jun-16 164 30 12 42 7.3
Jul-16 157 29 12 41 7.0
Aug-16 155 27 11 38 6.4
Sep-16 149 27 12 39 6.2
Oct-16 159 29 12 41 6.0
Nov-16 177 31 14 45 5.9
Dec-16 183 31 13 44 5.9
2016 Annual Avg 168 29 12 42 6.6
Jan-17 176 30 13 44 5.8
Feb-17 182 32 14 46 6.1
Mar-17 171 29 13 42 6.1
Apr-17 165 30 13 43 5.7
May-17 157 29 12 41 5.5
Jun-17 153 28 10 39 5.8
Jul-17 122 24 11 35 4.9
Aug-17 143 27 12 39 5.9
Sep-17 145 29 14 43 6.4
Oct-17 168 33 11 46 6.3
Nov-17 179 34 14 48 6.4
Dec-17 181 35 15 50 6.1
2017 Annual Avg 162 30 13 43 5.9
Jan-18 198 35 15 50 6.2
Feb-18 206 34 16 51 6.2
Mar-18 211 35 17 52 6.0
Apr-18 199 38 14 53 6.3
2018 Annual Avg 204 35 16 51 6.2
Grand Total Avg 170 30 13 44 6.2
Note: April 2018 data through 4/19/2018.
1
Table S.2 Monthly average SVI (mL/g) calculations for settleability test in 1000 mL plastic cylinder
Year January February March April May June July August September October November December Average
2014 - - - - 171 - 183 183 184 223 224 168 190
2015 216 227 201 145 155 190 169 146 177 180 269 273 190
2016 197 255 312 368 356 286 216 150 181 156 157 187 230
2017 194 178 171 196 202 217 255 232 250 206 245 271 215
2018 251 266 257
Table S.3 Monthly average SVI (mL/g) calculations for settleability test in 1000 mL glass beaker
Year January February March April May June July August September October November December Average
2017 218 189 191 211 245 205
2018 233 266 246
Table S.4 Monthly average MLSS (mg/L) concentrations collected from aerobic tank 2
Year January February March April May June July August September October November December Average
2014 - - - - 4840 3969 3814 4138 3100 2977 3309 4057 3715
2015 3718 3793 2778 3676 4360 3229 3224 3027 2777 4033 3369 3200 3430
2016 2703 3276 2993 2605 2564 3213 2922 2700 3706 4085 3324 4038 3223
2017 4194 4740 4871 4426 4458 4317 3635 3753 2983 3388 3524 3286 4016
2018 3744 3596 - - - - - - - - - - 3684
1
APPENDIX B
For reference, the Nine Springs Wastewater Treatment Plant facility permit is attached. The
Wisconsin Department of Natural Resources regulates point source dischargers through the
Wisconsin Pollutant Discharge Elimination System (WPDES) program. Because the NSWWTP
was in substantial compliance with the permit, the facility continued operating under this expired
permit until the Department was able to renew and reissue an updated permit. Permit cycles occur
every 5 years, thus it should be assumed that this attachment is no longer current to future research.
WPDES Permit No. WI-0024597-08-0
WPDES PERMIT
STATE OF WISCONSIN
DEPARTMENT OF NATURAL RESOURCES PERMIT TO DISCHARGE UNDER THE WISCONSIN POLLUTANT DISCHARGE
ELIMINATION SYSTEM
MADISON METROPOLITAN SEWERAGE DISTRICT
is permitted, under the authority of Chapter 283, Wisconsin Statutes, to discharge from a facility
located at
1610 Moorland Road, Madison,WI
to
BADFISH CREEK, FROM OUTFALL 001, AND GROUNDWATER OF THE YAHARA RIVER AND LAKE
MONONA WATERSHED, FROM OUTFALL 008, BOTH IN THE LOWER ROCK RIVER BASIN
AND TO
BADGER MILL CREEK, FROM OUTFALL 005, INTHE SUGAR-PECATONICA RIVER BASIN,
ALL IN DANE COUNTY
in accordance with the effluent limitations, monitoring requirements and other conditions set
forth in this permit.
The permittee shall not discharge after the date of expiration. If the permittee wishes to continue to discharge after
this expiration date an application shall be filed for reissuance of this permit, according to Chapter NR 200, Wis.
Adm. Code, at least 180 days prior to the expiration date given below.
State of Wisconsin Department of Natural Resources
For the Secretary
By _________________________
Kenneth Johnson
South Central Region Water Leader
_________________________
Date Permit Signed/Issued
PERMIT TERM: EFFECTIVE DATE - October 01, 2010 EXPIRATION DATE - September 30, 2015
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
TABLE OF CONTENTS
1 INFLUENT REQUIREMENTS 1
1.1 SAMPLING POINT(S) 1 1.2 MONITORING REQUIREMENTS 1
1.2.1 Sampling Point 701 - INFLUENT TO PLANT 1
2 IN-PLANT REQUIREMENTS 3
2.1 SAMPLING POINT(S) 3 2.2 MONITORING REQUIREMENTS AND LIMITATIONS 3
2.2.1 Sampling Point 111 - In plant mercury monitoring 3 2.2.2 Sampling Point 112 - Diversion structure 3
3 SURFACE WATER REQUIREMENTS 5
3.1 SAMPLING POINT(S) 5 3.2 MONITORING REQUIREMENTS AND EFFLUENT LIMITATIONS 5
3.2.1 Sampling Point (Outfall) 001 - EFFL/BADFISH CREEK 5 3.2.2 Sampling Point (Outfall) 005 - EFFL/BADGER MILL CREEK 8
4 LAND TREATMENT REQUIREMENTS 12
4.1 SAMPLING POINT(S) 12 4.2 MONITORING REQUIREMENTS AND LIMITATIONS 12
4.2.1 Sampling Point (Outfall) 008 - Golf Course Spray Irrigation, Spray Irrigation 12
5 LAND APPLICATION REQUIREMENTS 15
5.1 SAMPLING POINT(S) 15 5.2 MONITORING REQUIREMENTS AND LIMITATIONS 15
5.2.1 Sampling Points (Outfalls) 002, 009 and 010 15
6 SCHEDULES OF COMPLIANCE 20
6.1 MERCURY POLLUTANT MINIMIZATION PROGRAM 20 6.2 CHLORIDE TARGET VALUE 20
7 STANDARD REQUIREMENTS 21
7.1 REPORTING AND MONITORING REQUIREMENTS 21 7.1.1 Monitoring Results 21 7.1.2 Sampling and Testing Procedures 21 7.1.3 Pretreatment Sampling Requirements 21 7.1.4 Recording of Results 22 7.1.5 Reporting of Monitoring Results 22 7.1.6 Compliance Maintenance Annual Reports 22 7.1.7 Records Retention 22 7.1.8 Other Information 23
7.2 SYSTEM OPERATING REQUIREMENTS 23 7.2.1 Noncompliance Notification 23 7.2.2 Flow Meters 23 7.2.3 Raw Grit and Screenings 23 7.2.4 Sludge Management 23 7.2.5 Prohibited Wastes 24 7.2.6 Unscheduled Bypassing 24 7.2.7 Scheduled Bypassing 24 7.2.8 Proper Operation and Maintenance 25
7.3 SURFACE WATER REQUIREMENTS 25 7.3.1 Permittee-Determined Limit of Quantitation Incorporated into this Permit 25 7.3.2 Appropriate Formulas for Effluent Calculations 25
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
7.3.3 Visible Foam or Floating Solids 25 7.3.4 Percent Removal 25 7.3.5 Fecal Coliforms 26 7.3.6 Seasonal Disinfection 26 7.3.7 Whole Effluent Toxicity (WET) Monitoring Requirements 26 7.3.8 Whole Effluent Toxicity (WET) Identification and Reduction 26 7.3.9 Whole Effluent Toxicity (WET) and Chloride Source Reduction Measures 26
7.4 PRETREATMENT PROGRAM REQUIREMENTS 27 7.4.1 Inventories 27 7.4.2 Regulation of Industrial Users 27 7.4.3 Annual Pretreatment Program Report 29 7.4.4 Pretreatment Program Modifications 29 7.4.5 Program Resources 29
7.5 LAND TREATMENT (LAND DISPOSAL) REQUIREMENTS 29 7.5.1 Application of NR 140 to Substances Discharged 29 7.5.2 Appropriate Formulas for Nitrogen 29 7.5.3 Toxic or Hazardous Pollutants 30 7.5.4 Industrial Waste - Pretreatment Requirements 30 7.5.5 Overflow 30 7.5.6 Management Plan Requirements 30 7.5.7 Monthly Average Hydraulic Application Rate 30 7.5.8 Nitrogen Loading Requirements for Spray Irrigation 30 7.5.9 Runoff 30 7.5.10 Ponding 30 7.5.11 Frozen Ground 30 7.5.12 Land Treatment Annual Report 31
7.6 LAND APPLICATION REQUIREMENTS 31 7.6.1 Sludge Management Program Standards And Requirements Based Upon Federally Promulgated Regulations 31 7.6.2 General Sludge Management Information 31 7.6.3 Sludge Samples 31 7.6.4 Land Application Characteristic Report 31 7.6.5 Calculation of Water Extractable Phosphorus 31 7.6.6 Monitoring and Calculating PCB Concentrations in Sludge 31 7.6.7 Land Application Report 32 7.6.8 Other Methods of Disposal or Distribution Report 32 7.6.9 Approval to Land Apply 32 7.6.10 Soil Analysis Requirements 32 7.6.11 Land Application Site Evaluation 33 7.6.12 Class A Sludge: Fecal Coliform Density Requirement 33 7.6.13 Class A Sludge: Salmonella Density Requirements 33 7.6.14 Class B Sludge: Fecal Coliform Limitation 33 7.6.15 Vector Control: Volatile Solids Reduction 33 7.6.16 Class B Sludge - Vector Control: Incorporation 34
8 SUMMARY OF REPORTS DUE 35
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
1
1 Influent Requirements
1.1 Sampling Point(s)
Sampling Point Designation
Sampling
Point
Number
Sampling Point Location, WasteType/Sample Contents and Treatment Description (as applicable)
701 Influent to the wastewater treatment plant.
1.2 Monitoring Requirements The permittee shall comply with the following monitoring requirements.
1.2.1 Sampling Point 701 - INFLUENT TO PLANT
Monitoring Requirements and Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Flow Rate MGD Continuous Continuous
BOD5, Total mg/L Daily 24-Hr Flow
Prop Comp
Suspended Solids,
Total
mg/L Daily 24-Hr Flow
Prop Comp
Cadmium, Total
Recoverable
g/L Monthly 24-Hr Flow
Prop Comp
Chromium, Total
Recoverable
g/L Monthly 24-Hr Flow
Prop Comp
Copper, Total
Recoverable
g/L Monthly 24-Hr Flow
Prop Comp
Lead, Total
Recoverable
g/L Monthly 24-Hr Flow
Prop Comp
Nickel, Total
Recoverable
g/L Monthly 24-Hr Flow
Prop Comp
Zinc, Total
Recoverable
g/L Monthly 24-Hr Flow
Prop Comp
Mercury, Total
Recoverable
ng/L Monthly 24-Hr Flow
Prop Comp
1.2.1.1 Total Metals Analyses
Measurements of total metals and total recoverable metals shall be considered as equivalent.
1.2.1.2 Sample Analysis
Samples shall be analyzed using a method which provides adequate sensitivity so that results can be quantified, unless
not possible using the most sensitive approved method.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
2
1.2.1.3 Mercury Monitoring
The permittee shall collect and analyze all mercury samples according to the data quality requirements of ss. NR
106.145(9) and (10), Wisconsin Administrative Code. The limit of quantitation (LOQ) used for the effluent and field
blank shall be less than 1.3 ng/L, unless the samples are quantified at levels above 1.3 ng/L. The permittee shall
collect at least one mercury field blank for each set of mercury samples (a set of samples may include combinations of
intake, influent, effluent or other samples all collected on the same day). The permittee shall report results of samples
and field blanks to the Department on Discharge Monitoring Reports.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
3
2 In-Plant Requirements
2.1 Sampling Point(s)
Sampling Point Designation
Sampling
Point
Number
Sampling Point Location, WasteType/Sample Contents and Treatment Description (as applicable)
111 In plant mercury monitoring - collect a mercury field blank at the Effluent Building using the Clean
Hands/Dirty Hands sample collection procedure excerpted from EPA Method 1669.
112 Wet weather diversion structure to Nine Springs Creek tributary.
2.2 Monitoring Requirements and Limitations The permittee shall comply with the following monitoring requirements and limitations.
2.2.1 Sampling Point 111 - In plant mercury monitoring
Monitoring Requirements and Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Mercury, Total
Recoverable
ng/L Monthly Blank
2.2.1.1 Mercury Monitoring
The permittee shall collect and analyze all mercury samples according to the data quality requirements of ss. NR
106.145(9) and (10), Wisconsin Administrative Code. The limit of quantitation (LOQ) used for the effluent and field
blank shall be less than 1.3 ng/L, unless the samples are quantified at levels above 1.3 ng/L. The permittee shall
collect at least one mercury field blank for each set of mercury samples (a set of samples may include combinations of
intake, influent, effluent or other samples all collected on the same day). The permittee shall report results of samples
and field blanks to the Department on Discharge Monitoring Reports.
2.2.2 Sampling Point 112 - Diversion structure
Monitoring Requirements and Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Volume MGD Per
Occurrence
Estimated
Fecal Coliform #/100 ml Per
Occurrence
Grab
2.2.2.1 During wet weather high flow conditions, when necessary to maintain the proper function of the wastewater treatment
facility, the permittee may operate in-plant diversion facilities that have been designed and constructed for that
purpose. In-plant diversion shall only be used by the permittee when there are high wet weather wastewater flows to
the treatment facility and when such alternative operations are necessary to supplement effluent pumping capacity.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
4
2.2.2.2
The use of these facilities is authorized on the condition that the permittee shall: 1) implement a program of
management, operation, and maintenance of the sanitary sewage collection system that is designed to effectively
reduce, to the maximum extent practicable, the entry of wet weather flows into the sewerage system and, 2)
implement diversion option 4 as described in the February 8, 2005 Effluent Diversion Evaluation Report and as
approved by the Department.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
5
3 Surface Water Requirements
3.1 Sampling Point(s)
Sampling Point Designation
Sampling
Point
Number
Sampling Point Location, WasteType/Sample Contents and Treatment Description (as applicable)
001 Disinfected effluent sample point at Effluent Building - Nine Springs Wastewater Treatment Plant;
effluent discharged to Badfish Creek.
005 Same sample point as 001; effluent discharged to Badger Mill Creek.
3.2 Monitoring Requirements and Effluent Limitations The permittee shall comply with the following monitoring requirements and limitations.
3.2.1 Sampling Point (Outfall) 001 - EFFL/BADFISH CREEK
Monitoring Requirements and Effluent Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Flow Rate MGD Continuous Continuous
BOD5, Total Monthly Avg 19 mg/L Daily 24-Hr Comp
BOD5, Total Weekly Avg 20 mg/L Daily 24-Hr Comp
Suspended Solids,
Total
Monthly Avg 20 mg/L Daily 24-Hr Comp
Suspended Solids,
Total
Weekly Avg 23 mg/L Daily 24-Hr Comp
Dissolved Oxygen Daily Min 5.0 mg/L Daily Grab
pH Field Daily Max 9.0 su Daily Grab
pH Field Daily Min 6.0 su Daily Grab
Phosphorus, Total Monthly Avg 1.5 mg/L Daily 24-Hr Comp
Fecal Coliform Geometric
Mean
400 #/100 ml 2/Week Grab Limit applies April 15 -
October 15.
Nitrogen, Ammonia
(NH3-N) Total
Monthly Avg 1.8 mg/L Daily 24-Hr Comp Limit applies May -
September.
Nitrogen, Ammonia
(NH3-N) Total
Daily Max 17 mg/L Daily 24-Hr Comp Limit applies year-round.
Nitrogen, Ammonia
(NH3-N) Total
Weekly Avg 4.4 mg/L Daily 24-Hr Comp Limit applies May -
September.
Nitrogen, Ammonia
(NH3-N) Total
Monthly Avg 4.1 mg/L Daily 24-Hr Comp Limit applies October -
April.
Nitrogen, Ammonia
(NH3-N) Total
Weekly Avg 10 mg/L Daily 24-Hr Comp Limit applies October -
April.
Acute WET rTUa Quarterly 24-Hr Comp Sample during the quarters
specified in section 3.2.1.5 .
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
6
Monitoring Requirements and Effluent Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Chronic WET rTUc Quarterly 24-Hr Comp Sample during the quarters
specified in section 3.2.1.5 .
Cadmium, Total
Recoverable
g/L Monthly 24-Hr Comp
Chromium, Total
Recoverable
g/L Monthly 24-Hr Comp
Copper, Total
Recoverable
g/L Monthly 24-Hr Comp
Lead, Total
Recoverable
g/L Monthly 24-Hr Comp
Nickel, Total
Recoverable
g/L Monthly 24-Hr Comp
Zinc, Total
Recoverable
g/L Monthly 24-Hr Comp
Mercury, Total
Recoverable
Daily Max 5.7 ng/L Monthly Grab
BOD5, Total Monthly Avg 7,923 lbs/day Daily Calculated
BOD5, Total Weekly Avg 8,340 lbs/day Daily Calculated
Suspended Solids,
Total
Monthly Avg 8,340 lbs/day Daily Calculated
Suspended Solids,
Total
Weekly Avg 9,591 lbs/day Daily Calculated
Chloride Weekly Avg 481 mg/L Weekly 24-Hr Comp "This interim limit applies
until 09/30/2015 when the
target value of 430 mg/L
becomes effective as the
target limit. (See section
6.2)
Chloride Weekly Avg 200,000
lbs/day
Weekly Calculated
3.2.1.1 Total Metals Analyses
Measurements of total metals and total recoverable metals shall be considered as equivalent.
3.2.1.2 Sample Analysis
Samples shall be analyzed using a method which provides adequate sensitivity so that results can be quantified, unless
not possible using the most sensitive approved method.
3.2.1.3 Mercury Monitoring
The permittee shall collect and analyze all mercury samples according to the data quality requirements of ss. NR
106.145(9) and (10), Wisconsin Administrative Code. The limit of quantitation (LOQ) used for the effluent and field
blank shall be less than 1.3 ng/L, unless the samples are quantified at levels above 1.3 ng/L. The permittee shall
collect at least one mercury field blank for each set of mercury samples (a set of samples may include combinations of
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
7
intake, influent, effluent or other samples all collected on the same day). The permittee shall report results of samples
and field blanks to the Department on Discharge Monitoring Reports.
3.2.1.4 Non-Wet Weather and Alternative Wet Weather Mass Limit
This parameter (chloride) has a mass limit based on weather conditions. The applicable non-wet weather mass limit is
200,000 pounds/day. The applicable wet weather mass limit is 260,000 pounds/day. Report the applicable mass limit
on the Discharge Monitoring Report form in the variable limit column. See Standard Requirements for “Applicability
of Alternative Wet Weather Mass Limitations” and “Appropriate Formulas for Effluent Calculations”.
3.2.1.5 Whole Effluent Toxicity (WET) Testing
Primary Control Water: Control water shall be standard laboratory control water which has a hardness of +/- 10 %
of the hardness of: 1) the Yahara River above the confluence with Badfish Creek. Different control water may be used
if prior approval has been given by the Department.
Instream Waste Concentration (IWC): 93%
Dilution series: At least five effluent concentrations and dual controls must be included in each test.
Acute: 100, 50, 25, 12.5, 6.25% and any additional selected by the permittee.
Chronic: 100, 30, 10, 3, 1% (if the IWC <30%) or 100, 75, 50, 25, 12.5% (if the IWC >30%) and any
additional selected by the permittee.
WET Testing Frequency: Tests are required during the following quarters.
Acute: Jan – Mar 2011; April – June 2012; Oct – Dec 2013; July – Sep 2014; Jan – Mar 2015
Chronic: Jan – Mar and April – June 2011; April – June and July – Sep 2012; July – Sep and Oct –
Dec 2013; July – Sep and Oct – Dec 2014; Jan – Mar and April – June 2015
Reporting: The permittee shall report test results on the Discharge Monitoring Report form, and also complete the
"Whole Effluent Toxicity Test Report Form" (Section 6, "State of Wisconsin Aquatic Life Toxicity Testing Methods
Manual, 2nd
Edition"), for each test. The original, complete, signed version of the Whole Effluent Toxicity Test
Report Form shall be sent to the Biomonitoring Coordinator, Bureau of Watershed Management, 101 S. Webster St.,
P.O. Box 7921, Madison, WI 53707-7921, within 45 days of test completion. The original Discharge Monitoring
Report (DMR) form and one copy shall be sent to the contact and location provided on the DMR by the required
deadline.
Determination of Positive Results: An acute toxicity test shall be considered positive if the Toxic Unit - Acute (TUa)
is greater than 1.0 for either species. The TUa shall be calculated as follows: If LC50 ≥ 100, then TUa = 1.0. If LC50 is
< 100, then TUa = 100 ÷ LC50. A chronic toxicity test shall be considered positive if the Relative Toxic Unit - Chronic
(rTUc) is greater than 1.0 for either species. The rTUc shall be calculated as follows: If IC25 ≥ IWC, then rTUc = 1.0.
If IC25 < IWC, then rTUc = IWC ÷ IC25.
Additional Testing Requirements: Within 90 days of a test which showed positive results, the permittee shall submit
the results of at least 2 retests to the Biomonitoring Coordinator on "Whole Effluent Toxicity Test Report Forms". The
90 day reporting period shall begin the day after the test which showed a positive result. The retests shall be
completed using the same species and test methods specified for the original test (see the Standard Requirements
section herein).
3.2.1.6 Chloride Variance – Implement Source Reduction Measures
This permit contains a variance to the water quality-based effluent limit (WQBEL) for chloride granted in accordance
with s. NR 106.83(2), Wis. Adm. Code. As conditions of this variance the permittee shall (a) maintain effluent quality
at or below the interim effluent limitation specified in the table above, (b) implement the chloride source reduction
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
8
measures specified below, and (c) perform the actions listed in the compliance schedule. (See the Schedules of
Compliance section herein.):
1. Identify sources of chloride to the sewer system.
2. Require significant industrial and commercial contributors to evaluate their chloride discharges and make
recommendations for significantly reducing them, with the results of that evaluation being the basis for potential
restrictions of chloride discharges.
3. Educate homeowners on the impact of chloride from residential softeners, discuss options available for increasing
softener salt efficiency, and request voluntary reductions.
4. Recommend residential softener tune−ups on a voluntary basis.
5. Request voluntary support from local water softening businesses in the efforts described in subds. 2. and 3.
6. Educate licensed installers and self−installers of softeners on providing optional hard water for outside faucets for
residences.
3.2.1.7 Compliance with Dissolved Oxygen Limit
D.O. values of 4.5 mg/L or greater, as measured at sample point 001, will be deemed as compliant by the Department
for outfall 001based on the results of a previous study by the permittee sent to the Department on 8/18/1999 and
approved 9/22/1999. This study documented that the minimum D.O. gain across the Badfish Creek aerator was 0.5
mg/L.
3.2.1.8 Watershed-Based Trading to Meet Future Rock River TMDL Phosphorus Requirements
The District may implement watershed-based trading approaches to meet future phosphorus reduction goals that may
be required under a Total Maximum Daily Load for the Rock River Basin to the extent that such trading is authorized
under state statutes and approved by the Department.
3.2.2 Sampling Point (Outfall) 005 - EFFL/BADGER MILL CREEK
Monitoring Requirements and Effluent Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Flow Rate MGD Continuous Continuous
BOD5, Total Weekly Avg 16 mg/L Daily 24-Hr Comp Limit applies November -
April.
BOD5, Total Weekly Avg 7.0 mg/L Daily 24-Hr Comp Limit applies May -
October.
Suspended Solids,
Total
Monthly Avg 10 mg/L Daily 24-Hr Comp Limit applies May -
October.
Suspended Solids,
Total
Monthly Avg 16 mg/L Daily 24-Hr Comp Limit applies November -
April.
Dissolved Oxygen Daily Min 5.0 mg/L Daily Grab See section 3.2.2.7
regarding compliance with
this limit.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
9
Monitoring Requirements and Effluent Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
pH Field Daily Max 9.0 su Daily Grab
pH Field Daily Min 6.0 su Daily Grab
Phosphorus, Total Monthly Avg 1.5 mg/L Daily 24-Hr Comp
Fecal Coliform Geometric
Mean
400 #/100 ml 2/Week Grab Limit applies May -
September.
Nitrogen, Ammonia
(NH3-N) Total
Weekly Avg 8.7 mg/L Daily 24-Hr Comp Limit applies October -
April.
Nitrogen, Ammonia
(NH3-N) Total
Weekly Avg 2.6 mg/L Daily 24-Hr Comp Limit applies May -
September.
Nitrogen, Ammonia
(NH3-N) Total
Monthly Avg 3.8 mg/L Daily 24-Hr Comp Limit applies October -
April.
Nitrogen, Ammonia
(NH3-N) Total
Daily Max 11 mg/L Daily 24-Hr Comp Limit applies year-round.
Nitrogen, Ammonia
(NH3-N) Total
Monthly Avg 1.1 mg/L Daily 24-Hr Comp Limit applies May -
September.
Acute WET rTUa Quarterly 24-Hr Comp Sample during the quarters
specified in section 3.2.2.5 .
Chronic WET rTUc Quarterly 24-Hr Comp Sample during the quarters
specified in section 3.2.2.5 .
Chloride Weekly Avg 481 mg/L Weekly 24-Hr Comp This interim limit applies
until 09/30/2015 when the
target value of 430 mg/L
becomes effective as the
target limit. (See section
6.2)
Chloride Weekly Avg 14,000 lbs/day Weekly Calculated
Mercury, Total
Recoverable
Daily Max 5.7 ng/L Monthly Grab
3.2.2.1 Total Metals Analyses
Measurements of total metals and total recoverable metals shall be considered as equivalent.
3.2.2.2 Sample Analysis
Samples shall be analyzed using a method which provides adequate sensitivity so that results can be quantified, unless
not possible using the most sensitive approved method.
3.2.2.3 Mercury Monitoring
The permittee shall collect and analyze all mercury samples according to the data quality requirements of ss. NR
106.145(9) and (10), Wisconsin Administrative Code. The limit of quantitation (LOQ) used for the effluent and field
blank shall be less than 1.3 ng/L, unless the samples are quantified at levels above 1.3 ng/L. The permittee shall
collect at least one mercury field blank for each set of mercury samples (a set of samples may include combinations of
intake, influent, effluent or other samples all collected on the same day). The permittee shall report results of samples
and field blanks to the Department on Discharge Monitoring Reports.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
10
3.2.2.4 Non-Wet Weather and Alternative Wet Weather Mass Limit
This parameter (chloride) has a mass limit based on weather conditions. The applicable non-wet weather mass limit is
14,000 pounds/day. The applicable wet weather mass limit is not applicable to this outfall because all effluent is
pumped, with a maximum pump rate of 3.6 MGD. Report the applicable mass limit on the Discharge Monitoring
Report form in the variable limit column. See Standard Requirements for “Applicability of Alternative Wet Weather
Mass Limitations” and “Appropriate Formulas for Effluent Calculations”.
3.2.2.5 Whole Effluent Toxicity (WET) Testing
Primary Control Water: Control water shall be standard laboratory control water which has a hardness of +/- 10 %
of the hardness of: 1) the Sugar River above the confluence with Badger Mill Creek, for Outfall 005. Different control
water may be used if prior approval has been given by the Department.
Instream Waste Concentration (IWC): 97%
Dilution series: At least five effluent concentrations and dual controls must be included in each test.
Acute: 100, 50, 25, 12.5, 6.25% and any additional selected by the permittee.
Chronic: 100, 30, 10, 3, 1% (if the IWC <30%) or 100, 75, 50, 25, 12.5% (if the IWC >30%) and any
additional selected by the permittee.
WET Testing Frequency: Tests are required during the following quarters.
Acute: Jan – Mar 2011; April – June 2012; Oct – Dec 2013; July – Sep 2014; Jan – Mar 2015
Chronic: Jan – Mar and April – June 2011; April – June and July – Sep 2012; July – Sep and Oct –
Dec 2013; July – Sep and Oct – Dec 2014; Jan – Mar and April – June 2015
Reporting: The permittee shall report test results on the Discharge Monitoring Report form, and also complete the
"Whole Effluent Toxicity Test Report Form" (Section 6, "State of Wisconsin Aquatic Life Toxicity Testing Methods
Manual, 2nd
Edition"), for each test. The original, complete, signed version of the Whole Effluent Toxicity Test
Report Form shall be sent to the Biomonitoring Coordinator, Bureau of Watershed Management, 101 S. Webster St.,
P.O. Box 7921, Madison, WI 53707-7921, within 45 days of test completion. The original Discharge Monitoring
Report (DMR) form and one copy shall be sent to the contact and location provided on the DMR by the required
deadline.
Determination of Positive Results: An acute toxicity test shall be considered positive if the Toxic Unit - Acute (TUa)
is greater than 1.0 for either species. The TUa shall be calculated as follows: If LC50 ≥ 100, then TUa = 1.0. If LC50 is
< 100, then TUa = 100 ÷ LC50. A chronic toxicity test shall be considered positive if the Relative Toxic Unit - Chronic
(rTUc) is greater than 1.0 for either species. The rTUc shall be calculated as follows: If IC25 ≥ IWC, then rTUc = 1.0.
If IC25 < IWC, then rTUc = IWC ÷ IC25.
Additional Testing Requirements: Within 90 days of a test which showed positive results, the permittee shall submit
the results of at least 2 retests to the Biomonitoring Coordinator on "Whole Effluent Toxicity Test Report Forms". The
90 day reporting period shall begin the day after the test which showed a positive result. The retests shall be
completed using the same species and test methods specified for the original test (see the Standard Requirements
section herein).
3.2.2.6 Chloride Variance – Implement Source Reduction Measures
This permit contains a variance to the water quality-based effluent limit (WQBEL) for chloride granted in accordance
with s. NR 106.83(2), Wis. Adm. Code. As conditions of this variance the permittee shall (a) maintain effluent quality
at or below the interim effluent limitation specified in the table above, (b) implement the chloride source reduction
measures specified for Outfall 001, and (c) perform the actions listed in the compliance schedule. (See the Schedules
of Compliance section herein.)
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
11
3.2.2.7 Compliance with Dissolved Oxygen Limit
D.O. values of 3.8 mg/L or greater, as measured at sample point 001, will be deemed as compliant by the Department
for outfall 005 based on the results of a previous study by the permittee sent to the Department on 8/18/1999 and
approved 9/22/1999. This study documented that the minimum D.O. gain across the Badger Mill Creek aerator was
1.2 mg/L.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
12
4 Land Treatment Requirements
4.1 Sampling Point(s)
Sampling Point Designation
Sampling
Point
Number
Sampling Point Location, Waste Description/Sample Contents and Treatment Description (as
applicable)
008 Demonstration project - spray irrigation of final effluent on golf course.
4.2 Monitoring Requirements and Limitations The permittee shall comply with the following monitoring requirements and limitations.
4.2.1 Sampling Point (Outfall) 008 - Golf Course Spray Irrigation, Spray Irrigation
Monitoring Requirements and Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Flow Rate gal Daily Total Daily
Hydraulic
Application Rate
Monthly Avg 10,000
gal/ac/day
Monthly Calculated
BOD5, Total Monthly Avg 16 mg/L Monthly 24-Hr Flow
Prop Comp
Use sample result from
outfall 001.
Suspended Solids,
Total
mg/L Monthly 24-Hr Flow
Prop Comp
Use sample result from
outfall 001.
pH Field su Monthly Grab Use sample result from
outfall 001.
Nitrogen, Total
Kjeldahl
mg/L Monthly 24-Hr Flow
Prop Comp
Use sample result from
outfall 001.
Nitrogen, Ammonia
(NH3-N) Total
mg/L Monthly 24-Hr Flow
Prop Comp
Use sample result from
outfall 001.
Nitrogen, Organic
Total
mg/L Monthly Calculated Use sample result from
outfall 001.
Nitrogen, Nitrite +
Nitrate Total
mg/L Monthly 24-Hr Flow
Prop Comp
Use sample result from
outfall 001.
Nitrogen, Total mg/L Monthly Calculated Use sample result from
outfall 001.
Chloride mg/L Monthly 24-Hr Flow
Prop Comp
Use sample result from
outfall 001.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
13
Monitoring Requirements and Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Solids, Total
Dissolved
mg/L Monthly 24-Hr Flow
Prop Comp
Use sample result from
outfall 001.
Nitrogen, Max
Applied On Any
Zone
lbs/ac/yr Annual Total
Annual
Fecal Coliform Geometric
Mean
400 #/100 ml 2/Week Grab Use sample result from
outfall 001.
Phosphorus, Total mg/L Daily 24-Hr Flow
Prop Comp
Use sample result from
outfall 001.
Daily Log – Monitoring Requirements and Limitations All discharge and monitoring activity shall be documented on log sheets. Originals of the log sheets shall be kept by
the permittee as described under “Records Retention” in the Standard Requirements section, and if requested, made available to the Department.
Parameters Limit Units Sample
Frequency
Sample
Type
Zone or Location Being Sprayed - Number As Needed Log
Acres Being Sprayed - Acres As Needed Log
Start to End Time - Date, Hour As Needed Log
Wastewater Loading Volume - Gallons As Needed Log
Wastewater Loading Volume - Gallons/Acre As Needed Calculated
Visual Observations - - As Needed Log
Annual Report – Monitoring Requirements and Limitations The Annual Report is due by January 31
st of each year for the previous calendar year.
Parameters Limit Units Sample
Frequency
Sample
Type
Total Volume Applied Per Zone - Gallons Annual Total
Annual
Total Volume Applied Per Zone - Gallons/Acre Annual Total
Annual
Total Nitrogen Applied per Zone - Pounds/Acre/Year Annual Calculated
Soil Analysis - - Annual Composite
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
14
Annual Report – Monitoring Requirements and Limitations The Annual Report is due by January 31
st of each year for the previous calendar year.
Parameters Limit Units Sample
Frequency
Sample
Type
Fertilizer Used - Pounds/Acre/Year Annual Total
Annual
Note: Inches/load cycle = gallons/acre/load cycle divided by 27,154.
4.2.1.1 Monthly Avg Flow – LT Calculation
The monthly average discharge flow for Land Treatment systems is calculated by dividing the total wastewater volume
discharged for the month by the total number of days in the month.
4.2.1.2 Spray Irrigation Site - Soil Analysis
The soil at each spray irrigation site shall be tested annually for nitrate-nitrogen, available phosphorus, available
potassium and pH.
4.2.1.3 Additional Demonstration Irrigation Project Requirements at Outfall 008
Irrigation may be conducted at Outfall 008 under the following conditions:
1. Prior Approval Necessary for Equipment or Operational Changes: The District shall provide written
notice to the department in advance of substantive changes to equipment or operating procedures at this
outfall. The written notice shall provide information on the proposed changes.
2. Application of Effluent: Effluent shall only be applied by direct irrigation and may not be applied during
times of the day when the golf course is open for golfing or during times when wind conditions may be
expected to cause significant drift.
3. Irrigation Season: Effluent may only be applied during the period of April 15th through October 15
th.
4. Irrigation Ponds: Effluent storage in irrigation ponds shall only be done according to a department-
approved management plan.
5. Soil Samples: A routine soil sample shall be collected from each spray field according to current UW
Soils Dept. methods, and tested for the purpose of obtaining plant available nutrients and for making
fertilizer and liming recommendations for the cover crop being grown.
6. Golf Course Signage: Adequate signage shall be placed in each area where effluent is used, advising the
public that the test plot is being irrigated using non-potable treated effluent and that all golfers or other
persons using the areas should practice good personal hygiene and hand washing before eating, drinking or
smoking.
4.2.1.4 Additional Demonstration Irrigation Projects at Other Sites
The District may conduct other effluent reuse demonstration projects subject to prior review and approval by DNR and
to terms/conditions specified by DNR.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
15
5 Land Application Requirements
In order for biosolids to be land applied it must at a minimum, meet all of the following criteria: the ceiling
concentration limits for metals established in this permit; Class B pathogen requirements established in this permit;
and one of the vector control requirements specified in this permit.
The permittee may publicly distribute biosolids if it meets the exceptional quality (EQ) criteria specified in s. NR
204.03(19). These criteria require EQ biosolids to meet the following: the high quality metal concentration limits;
Class A process requirements for pathogens as well as either a fecal coliform limit of less than 1000 MPN/g TS or a
Salmonella limit of less than 3 MPN/4g TS; and one of the process requirements for vector attraction reduction. If the
biosolids do not meet the exceptional quality criteria specified in s. NR 204.03(19), the permitttee may not publicly
distribute the biosolids, but the biosolids may be land applied if the minimum criteria specified in this section are met.
5.1 Sampling Point(s) The discharge(s) shall be limited to land application of the waste type(s) designated for the listed sampling point(s) on
Department approved land spreading sites or by hauling to another facility.
Sampling Point Designation
Sampling
Point
Number
Sampling Point Location, WasteType/Sample Contents and Treatment Description (as applicable)
002 Anaerobically digested, gravity belt thickened liquid sludge. Monitoring shall apply only when this
outfall is active.
009 Sequencing batch temperature phased anaerobically digested liquid sludge. Notify the Department
when this outfall becomes active.
010 Sequencing batch temperature phased anaerobically digested, centrifuged cake sludge. Notify the
Department when this outfall becomes active.
5.2 Monitoring Requirements and Limitations The permittee shall comply with the following monitoring requirements and limitations.
5.2.1 Sampling Points (Outfalls) 002, 009 and 010
Monitoring Requirements and Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Solids, Total Percent 1/ 2 Months Composite
Arsenic Dry Wt High Quality 41 mg/kg 1/ 2 Months Composite Sample 010 annually.
Arsenic Dry Wt Ceiling 75 mg/kg 1/ 2 Months Composite
Cadmium Dry Wt High Quality 39 mg/kg 1/ 2 Months Composite Sample 010 annually.
Cadmium Dry Wt Ceiling 85 mg/kg 1/ 2 Months Composite
Copper Dry Wt High Quality 1,500 mg/kg 1/ 2 Months Composite Sample 010 annually.
Copper Dry Wt Ceiling 4,300 mg/kg 1/ 2 Months Composite
Lead Dry Wt High Quality 300 mg/kg 1/ 2 Months Composite Sample 010 annually.
Lead Dry Wt Ceiling 840 mg/kg 1/ 2 Months Composite
Mercury Dry Wt High Quality 17 mg/kg 1/ 2 Months Composite Sample 010 annually.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
16
Monitoring Requirements and Limitations
Parameter Limit Type Limit and
Units
Sample
Frequency
Sample
Type
Notes
Mercury Dry Wt Ceiling 57 mg/kg 1/ 2 Months Composite
Molybdenum Dry Wt Ceiling 75 mg/kg 1/ 2 Months Composite Sample 010 annually.
Nickel Dry Wt High Quality 420 mg/kg 1/ 2 Months Composite Sample 010 annually.
Nickel Dry Wt Ceiling 420 mg/kg 1/ 2 Months Composite
Selenium Dry Wt Ceiling 100 mg/kg 1/ 2 Months Composite Sample 010 annually.
Selenium Dry Wt High Quality 100 mg/kg 1/ 2 Months Composite
Zinc Dry Wt High Quality 2,800 mg/kg 1/ 2 Months Composite Sample 010 annually.
Zinc Dry Wt Ceiling 7,500 mg/kg 1/ 2 Months Composite Sample 010 annually.
Nitrogen, Total
Kjeldahl
Percent 1/ 2 Months Composite Sample 010 annually.
Nitrogen, Ammonium
(NH4-N) Total
Percent 1/ 2 Months Composite Sample 010 annually.
Phosphorus, Total Percent 1/ 2 Months Composite Sample 010 annually.
Potassium, Total
Recoverable
Percent 1/ 2 Months Composite Sample 010 annually.
Municipal Sludge Priority Pollutant Scan Once Composite As specified in ch. NR
215.03 (1-4), Wis. Adm.
Code. Sample Outfall 002
only, in 2013.
Other Sludge Requirements
Sludge Requirements Sample Frequency
List 3 Requirements – Pathogen Control: The requirements in List
3 shall be met prior to land application of sludge. Sample 002 or 009 Bimonthly.
Sample 010 Annually.
List 4 Requirements – Vector Attraction Reduction: The vector
attraction reduction shall be satisfied prior to, or at the time of land
application as specified in List 4.
Sample 002 or 009 Bimonthly.
Sample 010 Annually.
5.2.1.1 Exception to Bimonthly Sludge Sample Frequency
Where bimonthly sludge sampling is required, the requirement for the January – February period is hereby waived.
To compensate, a sixth sample shall be collected and reported during any of the other bimonthly report periods.
5.2.1.2 List 2 Analysis
If the monitoring frequency for List 2 parameters is more frequent than "Annual" then the sludge may be analyzed for
the List 2 parameters just prior to each land application season rather than at the more frequent interval specified.
5.2.1.3 Changes in Feed Sludge Characteristics
If a change in feed sludge characteristics, treatment process, or operational procedures occurs which may result in a
significant shift in sludge characteristics, the permittee shall reanalyze the sludge for List 1, 2, 3 and 4 parameters
each time such change occurs.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
17
5.2.1.4 Multiple Sludge Sample Points (Outfalls)
If there are multiple sludge sample points (outfalls), but the sludges are not subject to different sludge treatment
processes, then a separate List 2 analysis shall be conducted for each sludge type which is land applied, just prior to
land application, and the application rate shall be calculated for each sludge type. In this case, List 1, 3, and 4 and
PCBs need only be analyzed on a single sludge type, at the specified frequency. If there are multiple sludge sample
points (outfalls), due to multiple treatment processes, List 1, 2, 3 and 4 and PCBs shall be analyzed for each sludge
type at the specified frequency.
5.2.1.5 Sludge Which Exceeds the High Quality Limit
Cumulative pollutant loading records shall be kept for all bulk land application of sludge which does not meet the
high quality limit for any parameter. This requirement applies for the entire calendar year in which any exceedance of
Table 3 of s. NR 204.07(5)(c), is experienced. Such loading records shall be kept for all List 1 parameters for each
site land applied in that calendar year. The formula to be used for calculating cumulative loading is as follows:
[(Pollutant concentration (mg/kg) x dry tons applied/ac) ÷ 500] + previous loading (lbs/acre) = cumulative lbs
pollutant per acre
When a site reaches 90% of the allowable cumulative loading for any metal established in Table 2 of s. NR
204.07(5)(b), the Department shall be so notified through letter or in the comment section of the annual land
application report (3400-55).
5.2.1.6 Sludge Analysis for PCBs
The permittee shall analyze the sludge for Total PCBs one time during 2013. The results shall be reported as "PCB
Total Dry Wt". Either congener-specific analysis or Aroclor analysis shall be used to determine the PCB
concentration. The permittee may determine whether Aroclor or congener specific analysis is performed. Analyses
shall be performed in accordance with Table EM in s. NR 219.04, Wis. Adm. Code and the conditions specified in
Standard Requirements of this permit. PCB results shall be submitted by January 31, following the specified year of
analysis.
5.2.1.7 Lists 1, 2, 3, and 4
List 1
TOTAL SOLIDS AND METALS
See the Monitoring Requirements and Limitations table above for monitoring frequency and limitations for the
List 1 parameters
Solids, Total (percent)
Arsenic, mg/kg (dry weight)
Cadmium, mg/kg (dry weight)
Copper, mg/kg (dry weight)
Lead, mg/kg (dry weight)
Mercury, mg/kg (dry weight)
Molybdenum, mg/kg (dry weight)
Nickel, mg/kg (dry weight)
Selenium, mg/kg (dry weight)
Zinc, mg/kg (dry weight)
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
18
List 2
NUTRIENTS
See the Monitoring Requirements and Limitations table above for monitoring frequency for the List 2 parameters
Solids, Total (percent)
Nitrogen Total Kjeldahl (percent)
Nitrogen Ammonium (NH4-N) Total (percent)
Phosphorus Total as P (percent)
Phosphorus, Water Extractable (as percent of Total P)
Potassium Total Recoverable (percent)
List 3
PATHOGEN CONTROL FOR CLASS A SLUDGE
The permittee shall implement pathogen control as listed in List 3. The Department shall be notified of the pathogen
control utilized and shall be notified when the permittee decides to utilize alternative pathogen control.
The following requirements shall be met prior to land application of sludge.
Parameter Unit Limit
Fecal Coliform*
MPN/g TS 1,000
OR
Salmonella MPN/4g TS 3
AND, ONE OF THE FOLLOWING PROCESS OPTIONS
Temp/Time based on % Solids Alkaline Treatment
Prior test for Enteric Virus/Viable
Helminth Ova
Post test for Enteric Virus/Viable Helminth Ova
Composting Heat Drying
Heat Treatment Thermophilic Aerobic Digestion
Beta Ray Irradiation Gamma Ray Irradiation
Pasteurization PFRP Equivalent Process
* For Class A sludge, each sampling event shall satisfy the numerical standards specified above.
List 3
PATHOGEN CONTROL FOR CLASS B SLUDGE
The permittee shall implement pathogen control as listed in List 3. The Department shall be notified of the pathogen
control utilized and shall be notified when the permittee decides to utilize alternative pathogen control.
The following requirements shall be met prior to land application of sludge.
Parameter Unit Limit
Fecal Coliform*
MPN/gTS or
CFU/gTS 2,000,000
OR, ONE OF THE FOLLOWING PROCESS OPTIONS
Aerobic Digestion Air Drying
Anaerobic Digestion Composting
Alkaline Stabilization PSRP Equivalent Process
* The Fecal Coliform limit shall be reported as the geometric mean of 7 discrete samples on a dry weight basis.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
19
List 4
VECTOR ATTRACTION REDUCTION
The permittee shall implement any one of the vector attraction reduction options specified in List 4. The Department
shall be notified of the option utilized and shall be notified when the permittee decides to utilize an alternative option.
One of the following shall be satisfied prior to, or at the time of land application as specified in List 4.
Option Limit Where/When it Shall be Met
Volatile Solids Reduction 38% Across the process
Specific Oxygen Uptake Rate 1.5 mg O2/hr/g TS On aerobic stabilized sludge
Anaerobic bench-scale test <17 % VS reduction On anaerobic digested sludge
Aerobic bench-scale test <15 % VS reduction On aerobic digested sludge
Aerobic Process >14 days, Temp >40C and
Avg. Temp > 45C
On composted sludge
pH adjustment >12 S.U. (for 2 hours)
and >11.5
(for an additional 22 hours)
During the process
Drying without primary solids >75 % TS When applied or bagged
Drying with primary solids >90 % TS When applied or bagged
Equivalent
Process
Approved by the Department Varies with process
Injection - When applied
Incorporation - Within 6 hours of application
5.2.1.8 Daily Land Application Log
Daily Land Application Log
Discharge Monitoring Requirements and Limitations
The permittee shall maintain a daily land application log for biosolids land applied each day when land application
occurs. The following minimum records must be kept, in addition to all analytical results for the biosolids land
applied. The log book records shall form the basis for the annual land application report requirements.
NOTE: The Department considers the information maintained in the District’s Metrogro Database as
satisfying this requirement.
Parameters Units Sample
Frequency
DNR Site Number(s) Number Daily as used
Outfall number applied Number Daily as used
Acres applied Acres Daily as used
Amount applied As appropriate * /day Daily as used
Application rate per acre unit */acre Daily as used
Nitrogen applied per acre lb/acre Daily as used
Method of Application Injection, Incorporation, or surface
applied
Daily as used
*gallons, cubic yards, dry US Tons or dry Metric Tons
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
20
6 Schedules of Compliance
6.1 Mercury Pollutant Minimization Program The permittee shall implement or continue a pollutant minimization program whenever, after the first 24 months of
mercury monitoring, a mercury effluent limitation is necessary under the procedure in s. NR 106.145(2), Wis. Adm.
Code.
Required Action Date Due
Implement the Mercury Pollutant Minimization Program: The permittee shall implement the
PMP as submitted or as amended by agreement of the permittee and the Department.
Submit Annual Status Reports: The permittee shall submit to the Department an annual status
report on the progress of the PMP as required by s. NR 106.145(7), Wis. Adm. Code. Submittal of
each annual status report is required by March 31, annually.
Note: If the permittee wishes to apply for an alternative mercury effluent limitation, that application
is due with the application for permit reissuance by 6 months prior to permit expiration. The
permittee should submit or reference the PMP plan as updated by the Annual Status Report or more
recent developments as part of that application.
6.2 Chloride Target Value As a condition of the variance to the water quality based effluent limitation(s) for chloride granted in accordance with
s. NR 106.83(2), Wis. Adm. Code, the permittee shall perform the following actions.
Required Action Date Due
Annual Chloride Progress Report: Submit an annual progress report, that shall indicate which
chloride source reduction measures have been implemented. The report shall also include a
calculated annual mass discharge of chloride based on chloride sampling and flow data. After the
first progress report is submitted, the permittee may submit a written request to the department to
waive further annual progress reports. If after evaluating the progress of the source reduction
measures, the department decides to accommodate the request, the department shall notify the
permittee in writing that the subsequent annual reports are waived. The Final Chloride Report cannot
be waived and shall be submitted by the Date Due. Note that the interim limitation of 481 mg/L
remains enforceable until 9/30/2015, when the target value of 430 mg/L becomes effective. The first
annual chloride progress report is to be submitted by the Date Due.
06/30/2011
Annual Chloride Progress Report #2: Submit a chloride progress report. 06/30/2012
Annual Chloride Progress Report #3: Submit a chloride progress report. 06/30/2013
Annual Chloride Progress Report #4: Submit a chloride progress report. 06/30/2014
Final Chloride Report: Submit a final report documenting the success in meeting the chloride target
value of 430 mg/L, as well as the anticipated future reduction in chloride sources and chloride
effluent concentrations. This report shall also include proposed target values and source reduction
measures for negotiations with the department if the permittee intends to seek a renewed chloride
variance per s. NR 106.83, Wis. Adm. Code, for the reissued permit. Note that the target value is the
benchmark for evaluating the effectiveness of the chloride source reduction measures, but is not an
enforceable limitation until the last day of this permit, 09/30/2015.
06/30/2015
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7 Standard Requirements NR 205, Wisconsin Administrative Code: The conditions in ss. NR 205.07(1) and NR 205.07(2), Wis. Adm. Code,
are included by reference in this permit. The permittee shall comply with all of these requirements. Some of these
requirements are outlined in the Standard Requirements section of this permit. Requirements not specifically outlined
in the Standard Requirement section of this permit can be found in ss. NR 205.07(1) and NR 205.07(2).
7.1 Reporting and Monitoring Requirements
7.1.1 Monitoring Results
Monitoring results obtained during the previous month shall be summarized and reported on a Department
Wastewater Discharge Monitoring Report. The report may require reporting of any or all of the information specified
below under ‘Recording of Results’. This report is to be returned to the Department no later than the date indicated
on the form. When submitting a paper Discharge Monitoring Report form, the original and one copy of the
Wastewater Discharge Monitoring Report Form shall be submitted to the return address printed on the form. A copy
of the Wastewater Discharge Monitoring Report Form or an electronic file of the report shall be retained by the
permittee.
All Wastewater Discharge Monitoring Reports submitted to the Department should be submitted using the electronic
Discharge Monitoring Report system. Permittees who may be unable to submit Wastewater Discharge Monitoring
Reports electronically may request approval to submit paper DMRs upon demonstration that electronic reporting is
not feasible or practicable.
If the permittee monitors any pollutant more frequently than required by this permit, the results of such monitoring
shall be included on the Wastewater Discharge Monitoring Report.
The permittee shall comply with all limits for each parameter regardless of monitoring frequency. For example,
monthly, weekly, and/or daily limits shall be met even with monthly monitoring. The permittee may monitor more
frequently than required for any parameter.
An Electronic Discharge Monitoring Report Certification sheet shall be signed and submitted with each electronic
Discharge Monitoring Report submittal. This certification sheet, which is not part of the electronic report form, shall
be signed by a principal executive officer, a ranking elected official or other duly authorized representative and shall
be mailed to the Department at the time of submittal of the electronic Discharge Monitoring Report. The certification
sheet certifies that the electronic report form is true, accurate and complete. Paper reports shall be signed by a
principal executive officer, a ranking elected official, or other duly authorized representative.
7.1.2 Sampling and Testing Procedures
Sampling and laboratory testing procedures shall be performed in accordance with Chapters NR 218 and NR 219,
Wis. Adm. Code and shall be performed by a laboratory certified or registered in accordance with the requirements of
ch. NR 149, Wis. Adm. Code. Groundwater sample collection and analysis shall be performed in accordance with ch.
NR 140, Wis. Adm. Code. The analytical methodologies used shall enable the laboratory to quantitate all substances
for which monitoring is required at levels below the effluent limitation. If the required level cannot be met by any of
the methods available in NR 219, Wis. Adm. Code, then the method with the lowest limit of detection shall be
selected. Additional test procedures may be specified in this permit.
7.1.3 Pretreatment Sampling Requirements
Sampling for pretreatment parameters (cadmium, chromium, copper, lead, nickel, zinc, and mercury) shall be done
during a day each month when industrial discharges are occurring at normal to maximum levels. The sampling of the
influent and effluent for these parameters shall be coordinated. All 24 hour composite samples shall be flow
proportional.
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7.1.4 Recording of Results
The permittee shall maintain records which provide the following information for each effluent measurement or
sample taken:
the date, exact place, method and time of sampling or measurements;
the individual who performed the sampling or measurements;
the date the analysis was performed;
the individual who performed the analysis;
the analytical techniques or methods used; and
the results of the analysis.
7.1.5 Reporting of Monitoring Results
The permittee shall use the following conventions when reporting effluent monitoring results:
Pollutant concentrations less than the limit of detection shall be reported as < (less than) the value of the
limit of detection. For example, if a substance is not detected at a detection limit of 0.1 mg/L, report the
pollutant concentration as < 0.1 mg/L.
Pollutant concentrations equal to or greater than the limit of detection, but less than the limit of
quantitation, shall be reported and the limit of quantitation shall be specified.
For the purposes of reporting a calculated result, average or a mass discharge value, the permittee may
substitute a 0 (zero) for any pollutant concentration that is less than the limit of detection. However, if the
effluent limitation is less than the limit of detection, the department may substitute a value other than zero
for results less than the limit of detection, after considering the number of monitoring results that are
greater than the limit of detection and if warranted when applying appropriate statistical techniques.
7.1.6 Compliance Maintenance Annual Reports
Compliance Maintenance Annual Reports (CMAR) shall be completed using information obtained over each calendar
year regarding the wastewater conveyance and treatment system. The CMAR shall be submitted by the permittee in
accordance with ch. NR 208, Wis. Adm. Code, by June 30, each year on an electronic report form provided by the
Department.
In the case of a publicly owned treatment works, a resolution shall be passed by the governing body and submitted as
part of the CMAR, verifying its review of the report and providing responses as required. Private owners of
wastewater treatment works are not required to pass a resolution; but they must provide an Owner Statement and
responses as required, as part of the CMAR submittal.
A separate CMAR certification document, that is not part of the electronic report form, shall be mailed to the
Department at the time of electronic submittal of the CMAR. The CMAR certification shall be signed and submitted
by an authorized representative of the permittee. The certification shall be submitted by mail. The certification shall
verify the electronic report is complete, accurate and contains information from the owner’s treatment works.
7.1.7 Records Retention
The permittee shall retain records of all monitoring information, including all calibration and maintenance records and
all original strip chart recordings for continuous monitoring instrumentation, copies of all reports required by the
permit, and records of all data used to complete the application for the permit for a period of at least 3 years from the
date of the sample, measurement, report or application. All pertinent sludge information, including permit application
information and other documents specified in this permit or s. NR 204.06(9), Wis. Adm. Code shall be retained for a
minimum of 5 years.
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7.1.8 Other Information
Where the permittee becomes aware that it failed to submit any relevant facts in a permit application or submitted
incorrect information in a permit application or in any report to the Department, it shall promptly submit such facts or
correct information to the Department.
7.2 System Operating Requirements
7.2.1 Noncompliance Notification
The permittee shall report the following types of noncompliance by a telephone call to the Department's
regional office within 24 hours after becoming aware of the noncompliance:
any noncompliance which may endanger health or the environment;
any violation of an effluent limitation resulting from an unanticipated bypass;
any violation of an effluent limitation resulting from an upset; and
any violation of a maximum discharge limitation for any of the pollutants listed by the Department in
the permit, either for effluent or sludge.
A written report describing the noncompliance shall also be submitted to the Department's regional office
within 5 days after the permittee becomes aware of the noncompliance. On a case-by-case basis, the
Department may waive the requirement for submittal of a written report within 5 days and instruct the
permittee to submit the written report with the next regularly scheduled monitoring report. In either case,
the written report shall contain a description of the noncompliance and its cause; the period of
noncompliance, including exact dates and times; the steps taken or planned to reduce, eliminate and
prevent reoccurrence of the noncompliance; and if the noncompliance has not been corrected, the length
of time it is expected to continue.
NOTE: Section 292.11(2)(a), Wisconsin Statutes, requires any person who possesses or controls a hazardous
substance or who causes the discharge of a hazardous substance to notify the Department of Natural
Resources immediately of any discharge not authorized by the permit. The discharge of a hazardous
substance that is not authorized by this permit or that violates this permit may be a hazardous substance
spill. To report a hazardous substance spill, call DNR's 24-hour HOTLINE at 1-800-943-0003
7.2.2 Flow Meters
Flow meters shall be calibrated annually, as per s. NR 218.06, Wis. Adm. Code.
7.2.3 Raw Grit and Screenings
All raw grit and screenings shall be disposed of at a properly licensed solid waste facility or picked up by a licensed
waste hauler. If the facility or hauler are located in Wisconsin, then they shall be licensed under chs. NR 500-536,
Wis. Adm. Code.
7.2.4 Sludge Management
All sludge management activities shall be conducted in compliance with ch. NR 204 "Domestic Sewage Sludge
Management", Wis. Adm. Code.
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7.2.5 Prohibited Wastes
Under no circumstances may the introduction of wastes prohibited by s. NR 211.10, Wis. Adm. Code, be allowed into
the waste treatment system. Prohibited wastes include those:
which create a fire or explosion hazard in the treatment work;
which will cause corrosive structural damage to the treatment work;
solid or viscous substances in amounts which cause obstructions to the flow in sewers or interference with
the proper operation of the treatment work;
wastewaters at a flow rate or pollutant loading which are excessive over relatively short time periods so as
to cause a loss of treatment efficiency; and
changes in discharge volume or composition from contributing industries which overload the treatment
works or cause a loss of treatment efficiency.
7.2.6 Unscheduled Bypassing
Any unscheduled bypass or overflow of wastewater at the treatment works or from the collection system is prohibited,
and the Department may take enforcement action against a permittee for such occurrences under s. 283.89, Wis.
Stats., unless:
The bypass was unavoidable to prevent loss of life, personal injury, or severe property damage;
There were no feasible alternatives to the bypass, such as the use of auxiliary treatment facilities,
retention of untreated wastes, or maintenance during normal periods of equipment downtime. This
condition is not satisfied if adequate back-up equipment should have been installed in the exercise of
reasonable engineering judgment to prevent a bypass which occurred during normal periods of equipment
downtime or preventive maintenance; and
The permittee notified the Department as required in this Section.
Whenever there is an unscheduled bypass or overflow occurrence at the treatment works or from the collection
system, the permittee shall notify the Department within 24 hours of initiation of the bypass or overflow occurrence
by telephoning the wastewater staff in the regional office as soon as reasonably possible (FAX, email or voice mail, if
staff are unavailable).
In addition, the permittee shall within 5 days of conclusion of the bypass or overflow occurrence report the following
information to the Department in writing:
Reason the bypass or overflow occurred, or explanation of other contributing circumstances that resulted
in the overflow event. If the overflow or bypass is associated with wet weather, provide data on the
amount and duration of the rainfall or snow melt for each separate event.
Date the bypass or overflow occurred.
Location where the bypass or overflow occurred.
Duration of the bypass or overflow and estimated wastewater volume discharged.
Steps taken or the proposed corrective action planned to prevent similar future occurrences.
Any other information the permittee believes is relevant.
7.2.7 Scheduled Bypassing
Any construction or normal maintenance which results in a bypass of wastewater from a treatment system is
prohibited unless authorized by the Department in writing. If the Department determines that there is significant
public interest in the proposed action, the Department may schedule a public hearing or notice a proposal to approve
the bypass. Each request shall specify the following minimum information:
proposed date of bypass;
estimated duration of the bypass;
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estimated volume of the bypass;
alternatives to bypassing; and
measures to mitigate environmental harm caused by the bypass.
7.2.8 Proper Operation and Maintenance
The permittee shall at all times properly operate and maintain all facilities and systems of treatment and control which
are installed or used by the permittee to achieve compliance with the conditions of this permit. The wastewater
treatment facility shall be under the direct supervision of a state certified operator as required in s. NR 108.06(2), Wis.
Adm. Code. Proper operation and maintenance includes effective performance, adequate funding, adequate operator
staffing and training as required in ch. NR 114, Wis. Adm. Code, and adequate laboratory and process controls,
including appropriate quality assurance procedures. This provision requires the operation of back-up or auxiliary
facilities or similar systems only when necessary to achieve compliance with the conditions of the permit.
7.3 Surface Water Requirements
7.3.1 Permittee-Determined Limit of Quantitation Incorporated into this Permit
For pollutants with water quality-based effluent limits below the Limit of Quantitation (LOQ) in this permit, the LOQ
calculated by the permittee and reported on the Discharge Monitoring Reports (DMRs) is incorporated by reference
into this permit. The LOQ shall be reported on the DMRs, shall be the lowest quantifiable level practicable, and shall
be no greater than the minimum level (ML) specified in or approved under 40 CFR Part 136 for the pollutant at the
time this permit was issued, unless this permit specifies a higher LOQ.
7.3.2 Appropriate Formulas for Effluent Calculations
The permittee shall use the following formulas for calculating effluent results to determine compliance with average
limits and mass limits:
Weekly/Monthly average concentration = the sum of all daily results for that week/month, divided by the number
of results during that time period.
Weekly Average Mass Discharge (lbs/day): Daily mass = daily concentration (mg/L) x daily flow (MGD) x 8.34,
then average the daily mass values for the week.
Monthly Average Mass Discharge (lbs/day): Daily mass = daily concentration (mg/L) x daily flow (MGD) x 8.34,
then average the daily mass values for the month.
7.3.3 Visible Foam or Floating Solids
There shall be no discharge of floating solids or visible foam in other than trace amounts.
7.3.4 Percent Removal
During any 30 consecutive days, the average effluent concentrations of BOD5 and of total suspended solids shall not
exceed 15% of the average influent concentrations, respectively. This requirement does not apply to removal of total
suspended solids if the permittee operates a lagoon system and has received a variance for suspended solids granted
under NR 210.07(2), Wis. Adm. Code.
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7.3.5 Fecal Coliforms
The limit for fecal coliforms shall be expressed as a monthly geometric mean.
7.3.6 Seasonal Disinfection
Disinfection shall be provided from May 1 through September 30 of each year for the Badger Mill Creek Outfall
(005) and from April 15 through October 15 of each year for the Badfish Creek Outfall (001). Monitoring
requirements and the limitation for fecal coliforms apply only during the period in which disinfection is required.
Whenever chlorine is used for disinfection or other uses, the limitations and monitoring requirements for residual
chlorine shall apply. A dechlorination process shall be in operation whenever chlorine is used.
7.3.7 Whole Effluent Toxicity (WET) Monitoring Requirements
In order to determine the potential impact of the discharge on aquatic organisms, static-renewal toxicity tests shall be
performed on the effluent in accordance with the procedures specified in the "State of Wisconsin Aquatic Life Toxicity
Testing Methods Manual, 2nd
Edition" (PUB-WT-797, November 2004) as required by NR 219.04, Table A, Wis.
Adm. Code). All of the WET tests required in this permit, including any required retests, shall be conducted on the
Ceriodaphnia dubia and fathead minnow species. Receiving water samples shall not be collected from any point in
contact with the permittee's mixing zone and every attempt shall be made to avoid contact with any other discharge's
mixing zone.
7.3.8 Whole Effluent Toxicity (WET) Identification and Reduction
Within 60 days of a retest which showed positive results, the permittee shall submit a written report to the
Biomonitoring Coordinator, Bureau of Watershed Management, 101 S. Webster St., PO Box 7921, Madison, WI
53707-7921, which details the following:
A description of actions the permittee has taken or will take to remove toxicity and to prevent the
recurrence of toxicity;
A description of toxicity reduction evaluation (TRE) investigations that have been or will be done to
identify potential sources of toxicity, including some or all of the following actions:
(a) Evaluate the performance of the treatment system to identify deficiencies contributing to effluent
toxicity (e.g., operational problems, chemical additives, incomplete treatment)
(b) Identify the compound(s) causing toxicity
(c) Trace the compound(s) causing toxicity to their sources (e.g., industrial, commercial, domestic)
(d) Evaluate, select, and implement methods or technologies to control effluent toxicity (e.g., in-plant or
pretreatment controls, source reduction or removal)
Where corrective actions including a TRE have not been completed, an expeditious schedule under which
corrective actions will be implemented;
If no actions have been taken, the reason for not taking action.
The permittee may also request approval from the Department to postpone additional retests in order to investigate the
source(s) of toxicity. Postponed retests must be completed after toxicity is believed to have been removed.
7.3.9 Whole Effluent Toxicity (WET) and Chloride Source Reduction Measures
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Acute whole effluent toxicity testing requirements and acute whole effluent toxicity limitations may be held in
abeyance by the department until chloride source reduction actions are completed, according to s. NR 106.89, Wis.
Adm. Code, if either:
the permittee can demonstrate to the satisfaction of the department that the effluent concentration of chloride
exceeds 2,500 mg/L, or
the permittee can demonstrate to the satisfaction of the department that the effluent concentration of chloride
is less than 2,500 mg/L, but in excess of the calculated acute water quality-based effluent limitation, and
additional data are submitted which demonstrate that chloride is the sole source of acute toxicity.
Chronic whole effluent toxicity testing requirements and chronic whole effluent toxicity limitations may be held in
abeyance by the department until chloride source reduction actions are completed, according to s. NR 106.89, Wis.
Adm. Code, if either:
the permittee can demonstrate to the satisfaction of the department that the effluent concentration of chloride
exceeds 2 times the calculated chronic water quality-based effluent limitation, or
the permittee can demonstrate to the satisfaction of the department that the effluent concentration of chloride
is less than 2 times the calculated chronic water quality-based effluent limitation, but in excess of the
calculated chronic water quality-based effluent limitation, and additional data are submitted which
demonstrate that chloride is the sole source of chronic toxicity.
Following the completion of chloride source reduction activities, the department shall evaluate the need for whole
effluent toxicity monitoring and limitations.
7.4 Pretreatment Program Requirements The permittee is required to operate an industrial pretreatment program as described in the program initially approved
by the Department of Natural Resources including any subsequent program modifications approved by the
Department, and including commitments to program implementation activities provided in the permittee's annual
pretreatment program report, and that complies with the requirements set forth in 40 CFR Part 403 and ch. NR 211,
Wis. Adm. Code. To ensure that the program is operated in accordance with these requirements, the following
general conditions and requirements are hereby established:
7.4.1 Inventories
The permittee shall implement methods to maintain a current inventory of the general character and volume of
wastewater that industrial users discharge to the treatment works and shall provide an updated industrial user listing
annually and report any changes in the listing to the Department by March 31 of each year as part of the annual
pretreatment program report required herein.
7.4.2 Regulation of Industrial Users
7.4.2.1 Limitations for Industrial Users:
The permittee shall develop, maintain, enforce and revise as necessary local limits to implement the general and
specific prohibitions of the state and federal General Pretreatment Regulations.
7.4.2.2 Control Documents for Industrial Users (IUs)
The permittee shall control the discharge from each significant industrial user through individual discharge permits as
required by s. NR 211.235, Wis. Adm. Code and in accordance with the approved pretreatment program procedures
and the permittee's sewer use ordinance. The discharge permits shall be modified in a timely manner during the stated
term of the discharge permits according to the sewer use ordinance as conditions warrant. The discharge permits shall
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include at a minimum the elements found in s. NR 211.235(1), Wis. Adm. Code and references to the approved
pretreatment program procedures and the sewer use ordinance.
The permittee shall provide a copy of all newly issued, reissued, or modified discharge permits to the Department.
7.4.2.3 Review of Industrial User Reports, Inspections and Compliance Monitoring
The permittee shall require the submission of, receive, and review self-monitoring reports and other notices from
industrial users in accordance with the approved pretreatment program procedures. The permittee shall randomly
sample and analyze industrial user discharges and conduct surveillance activities to determine independent of
information supplied by the industrial users, whether the industrial users are in compliance with pretreatment
standards and requirements. The inspections and monitoring shall also be conducted to maintain accurate knowledge
of local industrial processes, including changes in the discharge, pretreatment equipment operation, spill prevention
control plans, slug control plans, and implementation of solvent management plans.
At least one time per year the permittee shall inspect and sample the discharge from each significant industrial user, or
more frequently if so specified in the permittee's approved pretreatment program. At least once every 2 years the
permittee shall evaluate whether each significant industrial user needs a slug control plan. If a slug control plan is
needed, the plan shall contain at a minimum the elements specified in s. NR 211.235(4)(b), Wis. Adm. Code.
7.4.2.4 Enforcement and Industrial User Compliance Evaluation & Violation Reports
The permittee shall enforce the industrial pretreatment requirements including the industrial user discharge limitations
of the permittee's sewer use ordinance. The permittee shall investigate instances of noncompliance by collecting and
analyzing samples and collecting other information with sufficient care to produce evidence admissible in
enforcement proceedings or in judicial actions. Investigation and response to instances of noncompliance shall be in
accordance with the permittee's sewer use ordinance and approved Enforcement Response Plan.
The permittee shall make a semiannual report on forms provided or approved by the Department. The semiannual
report shall include an analysis of industrial user significant noncompliance (i.e. the Industrial User Compliance
Evaluation, also known as the SNC Analysis) as outlined in s.NR 211.23(1)(j), Wis. Adm. Code, and a summary of
the permittee's response to all industrial noncompliance (i.e. the Industrial User Violation Report). The Industrial
User Compliance Evaluation Report shall include monitoring results received from industrial users pursuant to s.
NR 211.15(1)-(5), Wis. Adm. Code. The Industrial User Violation Report shall include copies of all notices of
noncompliance, notices of violation and other enforcement correspondence sent by the permittee to industrial users,
together with the industrial user's response. The Industrial User Compliance Evaluation and Violation Reports for the
period January through June shall be provided to the Department by September 30 of each year and for the period July
through December shall be provided to the Department by March 31 of the succeeding year, unless alternate submittal
dates are approved.
7.4.2.5 Publication of Violations
The permittee shall publish a list of industrial users that have significantly violated the municipal sewer use ordinance
during the calendar year, in the largest daily newspaper in the area by March 31 of the following year pursuant to s.
NR 211.23(1)(j), Wis. Adm. Code. A copy of the newspaper publication shall be provided as part of the annual
pretreatment report specified herein.
7.4.2.6 Multijurisdictional Agreements
The permittee shall establish agreements with all contributing jurisdictions as necessary to ensure compliance with
pretreatment standards and requirements by all industrial users discharging to the permittee's wastewater treatment
system. Any such agreement shall identify who will be responsible for maintaining the industrial user inventory,
issuance of industrial user control mechanisms, inspections and sampling, pretreatment program implementation, and
enforcement.
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7.4.3 Annual Pretreatment Program Report
The permittee shall evaluate the pretreatment program, and submit the Pretreatment Program Report to the
Department on forms provided or approved by the Department by March 31 annually, unless an alternate submittal
date is approved. The report shall include a brief summary of the work performed during the preceding calendar year,
including the numbers of discharge permits issued and in effect, pollution prevention activities, number of inspections
and monitoring surveys conducted, budget and personnel assigned to the program, a general discussion of program
progress in meeting the objectives of the permittee's pretreatment program together with summary comments and
recommendations.
7.4.4 Pretreatment Program Modifications
Future Modifications: The permittee shall within one year of any revisions to federal or state General
Pretreatment Regulations submit an application to the Department in duplicate to modify and update its
approved pretreatment program to incorporate such regulatory changes as applicable to the permittee.
Additionally, the Department or the permittee may request an application for program modification at any
time where necessary to improve program effectiveness based on program experience to date.
Modifications Subject to Department Approval: The permittee shall submit all proposed pretreatment
program modifications to the Department for determination of significance and opportunity for comment
in accordance with the requirements and conditions of s. NR 211.27, Wis. Adm. Code. Any substantial
proposed program modification shall be subject to Department public noticing and formal approval prior
to implementation. A substantial program modification includes, but is not limited to, changes in
enabling legal authority to administer and enforce pretreatment conditions and requirements; significant
changes in program administrative or operational procedures; significant reductions in monitoring
frequencies; significant reductions in program resources including personnel commitments, equipment,
and funding levels; changes (including any relaxation) in the local limitations for substances enforced and
applied to users of the sewerage treatment works; changes in treatment works sludge disposal or
management practices which impact the pretreatment program; or program modifications which increase
pollutant loadings to the treatment works. The Department shall use the procedures outlined in s. NR
211.30, Wis. Adm. Code for review and approval/denial of proposed pretreatment program modifications.
The permittee shall comply with local public participation requirements when implementing the
pretreatment program.
7.4.5 Program Resources
The permittee shall have sufficient resources and qualified personnel to carry out the pretreatment program
responsibilities as listed in ss. NR 211.22 and NR 211.23, Wis. Adm. Code.
7.5 Land Treatment (Land Disposal) Requirements
7.5.1 Application of NR 140 to Substances Discharged
This permit does not authorize the permittee to discharge any substance in a concentration which would cause an
applicable groundwater standard of ch. NR 140, Wis. Adm. Code, to be exceeded. The Department may seek a
response under NR 140 if the permittee’s discharge causes exceedance of an applicable groundwater standard for any
substance, including substances not specifically limited or monitored under this permit
7.5.2 Appropriate Formulas for Nitrogen
Total Nitrogen = Total Kjeldahl Nitrogen (mg/L) + [NO2 + NO3] Nitrogen (mg/L)
Organic Nitrogen (mg/L) = Total Kjeldahl Nitrogen (mg/L) - Ammonia Nitrogen (mg/L)
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7.5.3 Toxic or Hazardous Pollutants
The discharge of toxic or hazardous pollutants to land treatment systems is prohibited unless the applicant can
demonstrate and the department determines that the discharge of such pollutants will be in such small quantities that
no detrimental effect on groundwater or surface water will result pursuant to s. NR 206.07(2)(c), Wis. Adm. Code.
The criteria used shall include but not be limited to the toxicity of the pollutant, capacity of the soil to remove the
pollutant, degradability, usual or potential presence of the pollutant in the existing environment, method of application
and all other relevant factors.
7.5.4 Industrial Waste - Pretreatment Requirements
Industrial waste discharges tributary to municipal land treatment systems shall be in compliance with the applicable
pretreatment standards under ch. NR 211 Wis. Adm. Code pursuant to s. NR 206.07(2)(e), Wis. Adm. Code.
7.5.5 Overflow
Discharge to a land treatment system shall be limited so that the discharge and any precipitation which falls within the
boundary of the disposal system during such discharge does not overflow the boundary of the system unless the
WPDES permit authorizes collection and discharge of runoff to surface water pursuant to s. NR 206.07(2)(g), Wis.
Adm. Code.
7.5.6 Management Plan Requirements
All land treatment systems shall be operated in accordance with an approved management plan. The management
plan shall conform to the requirements of s. NR 110.25(3m), Wis. Adm. Code, per s. NR 206.07(2)(h), Wis. Adm.
Code
7.5.7 Monthly Average Hydraulic Application Rate
Determine the monthly average hydraulic application rate (in gal/acre/day) for each outfall by calculating the total
gallons of wastewater applied onto the site for the month, dividing that total by the number of wetted acres loaded
during the month, and then dividing this resulting value by the number of days in the month. Enter this calculated
monthly average value on the Discharge Monitoring Report form in the box for the last day of the month, in the
"Hydraulic Application Rate" column.
7.5.8 Nitrogen Loading Requirements for Spray Irrigation
The annual total pounds of nitrogen applied to the irrigation acreage shall be restricted to the annual nitrogen needs of
the cover crop as specified in the irrigation annual report table. The Department may approve an alternate nitrogen
loading limit in the management plan, pursuant to s. NR 206.06, Wis. Adm. Code.
7.5.9 Runoff
Discharge shall be limited to prevent any runoff of effluent from the spray irrigation site. Wastewater may not be
sprayed during any rainfall event that causes runoff from the site, pursuant to s. NR 206.08(2)(b)1,Wis. Adm. Code.
7.5.10 Ponding
The volume of discharge to a spray irrigation system shall be limited to prevent ponding, except for temporary
conditions following rainfall events, pursuant to s. NR 206.08(2)(b)2, Wis. Adm. Code.
7.5.11 Frozen Ground
Spray irrigation onto frozen ground is prohibited, pursuant to s. NR 110.255(2)(a)2, Wis. Adm. Code.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
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7.5.12 Land Treatment Annual Report
Annual Land Treatment Reports are due by January 31st
of each year for the previous calendar year.
7.6 Land Application Requirements
7.6.1 Sludge Management Program Standards And Requirements Based Upon Federally Promulgated Regulations
In the event that new federal sludge standards or regulations are promulgated, the permittee shall comply with the new
sludge requirements by the dates established in the regulations, if required by federal law, even if the permit has not
yet been modified to incorporate the new federal regulations.
7.6.2 General Sludge Management Information
The General Sludge Management Form 3400-48 shall be completed and submitted prior to any significant sludge
management changes.
7.6.3 Sludge Samples
All sludge samples shall be collected at a point and in a manner which will yield sample results which are
representative of the sludge being tested, and collected at the time which is appropriate for the specific test.
7.6.4 Land Application Characteristic Report
Each report shall consist of a Characteristic Form 3400-49 and Lab Report, unless approval for not submitting the lab
reports has been given. Both reports shall be submitted by January 31 following each year of analysis.
The permittee shall use the following convention when reporting sludge monitoring results: Pollutant concentrations
less than the limit of detection shall be reported as < (less than) the value of the limit of detection. For example, if a
substance is not detected at a detection limit of 1.0 mg/kg, report the pollutant concentration as < 1.0 mg/kg .
All results shall be reported on a dry weight basis.
7.6.5 Calculation of Water Extractable Phosphorus
The permittee shall use the following formula to calculate and report Water Extractable Phosphorus:
Water Extractable Phosphorus (% of Total P) =
[Water Extractable Phosphorus (mg/kg, dry wt) ÷ Total Phosphorus (mg/kg, dry wt)] x 100
7.6.6 Monitoring and Calculating PCB Concentrations in Sludge
When sludge analysis for “PCB, Total Dry Wt” is required by this permit, the PCB concentration in the sludge shall
be determined as follows.
Either congener-specific analysis or Aroclor analysis shall be used to determine the PCB concentration. The permittee
may determine whether Aroclor or congener specific analysis is performed. Analyses shall be performed in
accordance with the following provisions and Table EM in s. NR 219.04, Wis. Adm. Code.
EPA Method 1668 may be used to test for all PCB congeners. If this method is employed, all PCB
congeners shall be delineated. Non-detects shall be treated as zero. The values that are between the limit
of detection and the limit of quantitation shall be used when calculating the total value of all congeners.
All results shall be added together and the total PCB concentration by dry weight reported. Note: It is
recognized that a number of the congeners will co-elute with others, so there will not be 209 results to
sum.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
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EPA Method 8082A shall be used for PCB-Aroclor analysis and may be used for congener specific
analysis as well. If congener specific analysis is performed using Method 8082A, the list of congeners
tested shall include at least congener numbers 5, 18, 31, 44, 52, 66, 87, 101, 110, 138, 141, 151, 153, 170,
180, 183, 187, and 206 plus any other additional congeners which might be reasonably expected to occur
in the particular sample. For either type of analysis, the sample shall be extracted using the Soxhlet
extraction (EPA Method 3540C) (or the Soxhlet Dean-Stark modification) or the pressurized fluid
extraction (EPA Method 3545A). If Aroclor analysis is performed using Method 8082A, clean up steps
of the extract shall be performed as necessary to remove interference and to achieve as close to a limit of
detection of 0.11 mg/kg as possible. Reporting protocol, consistent with s. NR 106.07(6)(e), should be as
follows: If all Aroclors are less than the LOD, then the Total PCB Dry Wt result should be reported as
less than the highest LOD. If a single Aroclor is detected then that is what should be reported for the
Total PCB result. If multiple Aroclors are detected, they should be summed and reported as Total PCBs.
If congener specific analysis is done using Method 8082A, clean up steps of the extract shall be
performed as necessary to remove interference and to achieve as close to a limit of detection of 0.003
mg/kg as possible for each congener. If the aforementioned limits of detection cannot be achieved after
using the appropriate clean up techniques, a reporting limit that is achievable for the Aroclors or each
congener for the sample shall be determined. This reporting limit shall be reported and qualified
indicating the presence of an interference. The lab conducting the analysis shall perform as many of the
following methods as necessary to remove interference:
3620C – Florisil 3611B - Alumina
3640A - Gel Permeation 3660B - Sulfur Clean Up (using copper shot instead of powder)
3630C - Silica Gel 3665A - Sulfuric Acid Clean Up
7.6.7 Land Application Report
Land Application Report Form 3400-55 shall be submitted by January 31, following each year non-exceptional
quality sludge is land applied. Non-exceptional quality sludge is defined in s. NR 204.07(4), Wis. Adm. Code.
7.6.8 Other Methods of Disposal or Distribution Report
The permittee shall submit Report Form 3400-52 by January 31, following each year sludge is hauled, landfilled,
incinerated, or when exceptional quality sludge is distributed or land applied.
7.6.9 Approval to Land Apply
Bulk non-exceptional quality sludge as defined in s. NR 204.07(4), Wis. Adm. Code, may not be applied to land
without a written approval letter or Form 3400-122 from the Department unless the Permittee has obtained permission
from the Department to self approve sites in accordance with s. NR 204.06 (6), Wis. Adm. Code. Analysis of sludge
characteristics is required prior to land application. Application on frozen or snow covered ground is restricted to the
extent specified in s. NR 204.07(3) (l), Wis. Adm. Code.
7.6.10 Soil Analysis Requirements
Each site requested for approval for land application must have the soil tested prior to use. Each approved site used
for land application must subsequently be soil tested such that there is at least one valid soil test in the four years prior
to land application. All soil sampling and submittal of information to the testing laboratory shall be done in
accordance with UW Extension Bulletin A-2100. The testing shall be done by the UW Soils Lab in Madison or
Marshfield, WI or at a lab approved by UW. The test results including the crop recommendations shall be submitted
to the DNR contact listed for this permit, as they are available. Application rates shall be determined based on the
crop nitrogen recommendations and with consideration for other sources of nitrogen applied to the site.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
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7.6.11 Land Application Site Evaluation
For non-exceptional quality sludge, as defined in s. NR 204.07(4), Wis. Adm. Code, a Land Application Site Request
Form 3400-053 shall be submitted to the Department for the proposed land application site. The Department will
evaluate the proposed site for acceptability and will either approve or deny use of the proposed site. The permittee
may obtain permission to approve their own sites in accordance with s. NR 204.06(6), Wis. Adm. Code.
7.6.12 Class A Sludge: Fecal Coliform Density Requirement
If fecal coliform density is used to demonstrate compliance with Class A requirements, the fecal coliform density,
which must be < 1000 MPN/g TS as required in s. NR 204.07, Wis. Adm. Code, shall be satisfied immediately after
the treatment process is completed. If the material is bagged or distributed at that time, no re-testing is required. If
the material is bagged, distributed or land applied at a later time, the sludge shall be re-tested and this requirement
satisfied at that time also, to ensure that regrowth of bacteria has not occurred. See Municipal Wastewater Sludge
Guidance Memo #3 (Fecal Coliform Monitoring - Sampling and Analytical Procedures).
7.6.13 Class A Sludge: Salmonella Density Requirements
If salmonella density is used to demonstrate compliance with Class A requirements, the salmonella density, which
must be < 3 MPN/4 g TS as required in s. NR 204.07, Wis. Adm. Code, shall be satisfied immediately after the
treatment process is completed. If the material is bagged or distributed at that time, no re-testing is required. If the
material is bagged, distributed or land applied at a later time, the sludge shall be re-tested and this requirement
satisfied at that time also, to ensure that regrowth of bacteria has not occurred.
7.6.14 Class B Sludge: Fecal Coliform Limitation
Compliance with the fecal coliform limitation for Class B sludge shall be demonstrated by calculating the geometric
mean of at least 7 separate samples. (Note that a Total Solids analysis must be done on each sample). The geometric
mean shall be less than 2,000,000 MPN or CFU/g TS. Calculation of the geometric mean can be done using one of
the following 2 methods.
Method 1:
Geometric Mean = (X1 x X2 x X3 …x Xn)1/n
Where X = Coliform Density value of the sludge sample, and where n = number of samples (at least 7)
Method 2:
Geometric Mean = antilog[(X1 + X2 + X3 …+ Xn) n]
Where X = log10 of Coliform Density value of the sludge sample, and where n = number of samples (at least 7)
Example for Method 2
Sample Number Coliform Density of Sludge Sample log10
1 6.0 x 105 5.78
2 4.2 x 106 6.62
3 1.6 x 106 6.20
4 9.0 x 105 5.95
5 4.0 x 105 5.60
6 1.0 x 106 6.00
7 5.1 x 105 5.71
The geometric mean for the seven samples is determined by averaging the log10 values of the coliform density and
taking the antilog of that value.
(5.78 + 6.62 + 6.20 + 5.95 + 5.60 + 6.00 + 5.71) 7 = 5.98
The antilog of 5.98 = 9.5 x 105
7.6.15 Vector Control: Volatile Solids Reduction
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
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The mass of volatile solids in the sludge shall be reduced by a minimum of 38% between the time the sludge enters
the digestion process and the time it either exits the digester or a storage facility. For calculation of volatile solids
reduction, the permittee shall use the Van Kleeck equation or one of the other methods described in "Determination of
Volatile Solids Reduction in Digestion" by J.B. Farrell, which is Appendix C of EPA's Control of Pathogens in
Municipal Wastewater Sludge (EPA/625/R-92/013). The Van Kleeck equation is:
VSR% = VSIN - VSOUT X 100
VSIN - (VSOUT X VSIN)
Where: VSIN = Volatile Solids in Feed Sludge (g VS/g TS)
VSOUT = Volatile Solids in Final Sludge (g VS/g TS)
VSR% = Volatile Solids Reduction, (Percent)
7.6.16 Class B Sludge - Vector Control: Incorporation
Class B sludge shall be incorporated within 6 hours of surface application, or as approved by the Department.
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
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8 Summary of Reports Due FOR INFORMATIONAL PURPOSES ONLY
Description Date Page
Mercury Pollutant Minimization Program -Implement the Mercury Pollutant
Minimization Program
See Permit 21
Mercury Pollutant Minimization Program -Submit Annual Status Reports See Permit 21
Chloride Target Value -Annual Chloride Progress Report June 30, 2011 21
Chloride Target Value -Annual Chloride Progress Report #2 June 30, 2012 21
Chloride Target Value -Annual Chloride Progress Report #3 June 30, 2013 21
Chloride Target Value -Annual Chloride Progress Report #4 June 30, 2014 21
Chloride Target Value -Final Chloride Report June 30, 2015 21
Compliance Maintenance Annual Reports (CMAR) by June 30, each year 22
Industrial User Compliance Evaluation and Violation Reports Semiannual 28
Pretreatment Program Report Annually 29
General Sludge Management Form 3400-48 prior to any
significant sludge
management changes
31
Characteristic Form 3400-49 and Lab Report by January 31
following each year
of analysis
31
Land Application Report Form 3400-55 by January 31,
following each year
non-exceptional
quality sludge is land
applied
32
Report Form 3400-52 by January 31,
following each year
sludge is hauled,
landfilled,
incinerated, or when
exceptional quality
sludge is distributed
or land applied
32
Annual Land Treatment Reports by January 31st of
each year for the
previous calendar
year
31
Wastewater Discharge Monitoring Report no later than the date
indicated on the form
21
WPDES Permit No. WI-0024597-08-0
MADISON METROPOLITAN SEWERAGE DISTRICT
36
Report forms shall be submitted to the address printed on the report form. Any facility plans or plans and
specifications for municipal, industrial, industrial pretreatment and non industrial wastewater systems shall be
submitted to the Bureau of Watershed Management, P.O. Box 7921, Madison, WI 53707-7921. All other submittals
required by this permit shall be submitted to:
Mr. Robert Liska, South Central Region, 3911 Fish Hatchery Road, Fitchburg, WI 53711-5397