This document summarizes a case study on how online process monitoring and automated control systems were implemented at a wastewater treatment facility to enhance performance, reduce operating costs, and improve process stability. Sensors were installed to monitor dissolved oxygen, phosphorus, and suspended solids levels. Automated control systems were then used to control aeration, chemical dosing, sludge wasting, and solid retention time. The results included 10-15% energy savings from aeration control, a 95% reduction in chemical usage, and more stable process operation compared to previous manual control methods.

1. Case Study - Enhanced Performance &
Reduced Operating Cost With Online
Process Monitoring and Automated Control
YSI WATER RESOURCE RECOVERY FACILITY WEBINAR SERIES
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2. Presenters
Bulbul Ahmed, Ph.D., P.E.
Process Engineer- Water Solutions at Sanitaire
9333 N 49th St., Brown Deer, WI 53223 USA
O 414.365.2369 C 414.242.6564
E bulbul.ahmed@xyleminc.com
Robert Smith, P.E., BCEE, Ph.D.
Applications Engineer- Water Solutions at YSI
1725 Brannum Ln, Yellow Springs, OH 45387 USA
O 937.767.7241 C 614.499.2884
E robert.smith@xyleminc.com
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3. Wastewater Treatment
Levels of Control
1. Manual based on manual samplings,
batch tests & laboratory measurements
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4. Wastewater Treatment
Levels of Control
1. Manual based on manual samplings,
batch tests & laboratory measurements
2. Manual based on online measurements
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5. Wastewater Treatment
Levels of Control
1. Manual based on manual samplings,
batch tests & laboratory measurements
2. Manual based on online measurements
3. Automatic with online measurements
and single-variable feedback control
4. Automatic with online measurements
and multi-variable intelligent control
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6. Activated Sludge Process Control
Influent
Return Activated Sludge (RAS)
Mixed liquor Effluent
Clarifier
AIR
Aeration tank
Waste
Activated
Sludge (WAS)
Chemical Feed
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7. Black River Falls, WI WWTP

8. Biological/Chemical Nutrient Removal
• Design / Average Flow: 0.86 / 0.60 MGD
Effluent Discharge Permit
BOD5 = 30 mg/l
TSS = 30 mg/l
TP = 1.0 mg/l
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9. Problem Statement
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• Manual blower speed adjustment based on online DO monitoring
(Level 2)
 Only able to control blower operation during work hours
 Unstable DO concentration in the aeration basin
• Manual Sludge wasting based on time (Level 1)
 Amount of sludge wasted was unknown
 What happens if valve failed to close
 What happens if valve is not closed on time
 Limited success in maintaining desired SRT or MLSS
concentration
• Manual chemical dosing (Level 1)
 Ferric chloride (FeCl3 ) for phosphorous removal
 Caustic to recover pH
 Daily composited samples / limited control

10. Process Performance Optimization
Objectives
Test following automatic control algorithms against manual control to
examine process stability, treatment performance, and chemical & energy
savings potentials
• Blower Driven Aeration Control
• Phosphorous Removal Chemical Dosing Control
• Operator Desired Solid Retention Time (SRT) Control
• Process Optimized SRT (Smart SRT) Control
• Operator Desired Mixed Liquor Suspended Solids (MLSS) Control
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11. Monitoring System
Improvements
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12. Smart Sensor Status Visibility
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13. Control System
Improvements
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14. Aeration Control

15. Aeration Monitoring
FDO® 700 IQ optical DO sensor
• Factory calibration – no user calibration
required
• Very stable - measurement / reference
optics identical
• Angled sensor for higher accuracy – no
false highs, less noise
• Less maintenance - No membranes,
electrolyte, electrodes
• Replaceable sensor cap lasts 2+ years
(2-yr. warranty)
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16. Blower Driven Aeration Control
DO
controller
DO
DO
setpoint
How does it work?
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17. With OSCAR Control
• Automatic blower speed control
(24/7)
• 10 to 15% energy savings (hourly
average)
Without OSCAR Control
• Manual blower speed control
• No control during night, weekend,
and holidays
• Waste of energy
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18. Chemical Dosing Control

19. How is ‘P’ Removed?
2 ways
1. Biological
2. Chemical
Basic concept:
‘P’ dissolved ‘P’ Particulate
‘P’

20. How is ‘P’ Removed?
2 ways
1. Biological
2. Chemical
Basic concept:
‘P’ dissolved ‘P’ Particulate ‘P’

21. Orthophosphate Monitoring
P700 IQ
• Inf. / eff. / MLSS
• Low reagent
consumption
• Lightweight 0.45 µm
filter
• Sample pump in
cabinet (dry)
• Auto cal. & cleaning
• 5-min. measurement
(yellow method)
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22. Controlling Effluent Soluble ‘P’
How does it work?
TPeff = PO4eff + TPeff SS
PO4 Controller
Effluent Solids
Phosphorus
(~0.25-1 mg/L)
PO4
controller
PO4 Setpoint
Chemical
(Ferric/alum)
P Removal
Soluble BOD for
Bio-P Removal
PO4
Analyzer
Aerobic ZoneAnaerobic Zone
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23. Analyzer/Control Performance
• Similar treatment performance
• 95% reduction in ferric chloride usage
• Complete elimination of caustic usage
• Payback period is less than 4 months
With Analyzer Installation
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24. Sludge Wasting Control

25. Sludge Age, MCRT, SRT, CRT
Qe, TSSe
V, MLSS
Qr, TSSr
Qw, TSSr
Qi, TSSi
Biomass in the system Solids entering / leaving the system÷
Note: F:M is related to these parameters through constants for growth and decay
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26. TSS Monitoring
ViSolid® 700 IQ
• Factory calibrated for mixed liquor
• mg TSS / L, % TSS
• Built-in ultrasonic cleaning – always on
• No wipers, no external mechanical
components
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27. What is SRT?
Solids Retention Time = average duration of time an
organism spends in the system
SRT =
Basin Mass
Mass wasted per day
=
Basin volume(m3) · MLSS (mg/l)
WAS Q(m3/day) · WAS TSS(mg/l)
=
kg
kg/day
= days
Volume
MLSS
TSS
Q
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28. SIMS – Solids Inventory Management System
Automated sludge wasting to maintain a required
solids retention time or mixed liquor suspended
solids concentration
Benefits:
• Overall improvement and consistency in
effluent quality
• Improved stability of plant operation
• Improved settling characteristics
• Reduced energy use associated with aeration
and sludge handling
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29. SIMS Benefits
Ammonia
removal
efficiency
[kg NH3/kWh]
Power
Inadequate
treatment
Optimized
treatment
Wasted
energy
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30. SIMS Control Flexibility
Time
Four available modes of control
Set your
preferred
wasting
time
MLSS SRT Smart SRT
Set your
preferred run
time or volume
for each
wasting event
Control to an
operator
selected
MLSS
Control to an
operator
selected SRT
Control to an
optimized SRT
calculated based
on real-time
process
parameters
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31. Trouble-Free Control
Careful and stable adjustments ensure a healthy biomass
• Avoids fast process changes
• Maintains a healthy SRT also in MLSS mode
Trouble- free control
• We know our probes:
• Automatic detection of probe cleaning or calibration needs
• During probe maintenance, SIMS switch to a separate control mode to avoid
control using invalid data
• We know the process:
• Automatic detection of process upsets or unhealthy biomass
• As issues are detected, SIMS switch to a safe mode and an alarm is sent to the
operator

32. Operator Desired Solid Retention Time
(SRT) Control
Without OSCAR Control
• SRT varies of 8 to 22 days
• Potentials for under
treatment or over treatment
• Waste of energy
• Tedious manual wasting
With OSCAR Control
• Automatic Wasting
• Stable operator desired SRT
• Optimized treatment
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33. Operator Desired Mixed Liquor Suspended
Solids (MLSS) Control
Without OSCAR Control
• MLSS concentration varies
from 1900 to 2600 mg/l
• Wanted to maintain 2000 mg/l
but over/under shoot are due
to manual wasting
• No control during weekend or
holidays
With OSCAR Control
• MLSS was maintained close to the
setpoint (2100 mg/l) by automatic wasting
• Stable MLSS concentration over long
operational period
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34. Process Optimized SRT (Smart SRT)
Control
Desired Treatment
• Effluent ammonia concentration
less than 1.0 mg/l
Without OSCAR Control
• Manual wasting
With OSCAR Control
• Desired SRT was calculated
based on process parameters
• Maintained SRT by automatic
wasting adjustment
• Effluent ammonia conc. was
always less than 1.0 mg/l
• Optimized process operation
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35. Summary of Project

36. OSCARTM Process Performance Optimizer
Process Stability
DO
Manual control: 2.6 ± 1.6 mg/l
Automatic control: 2.0 ± 0.05 mg/l
10 to 15% energy savings
MLSS
Manual control: 1,900 to 2,600 mg/l
Automatic control: 2,037 ± 40 mg/l
SRT
Manual control: Varies from 8 to 21 days
Automatic control: 13.57 ± 0.13 days
Chemical dosing
Manual control: up to 1,000 gal. Ferric/day
Automatic control: Less than 50 gal./day
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37. Implementation of Online Monitoring and
OSCARTM Control
Automatic vs. Manual control
‘We love the way the OSCAR™ aeration control system is automatically controlling blower
speed and operation, and maintaining stable DO concentration that we never achieved during
manual operation. Currently, we do not need to worry about blower operation during work days,
weekends or long weekends.’
‘Historically, we ran our waste activated sludge pump manually for a certain period of time per
day. We love the way the OSCAR™ SIMS control system is automatically controlling wasting
based on our need, maintaining stable operation and providing superior effluent quality.’
‘We realized significant FeCl3 and caustic cost savings during the first 1.5 months of the YSI
Orthophosphate analyzer installation. We also completely eliminated caustic usages due to
controlled FeCl3 dosing.
Rick and Bill
Black River Falls WWTP Operators
Black River Falls, WI
Phone:715-284-2913
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38. IQ SensorNet Process Monitoring System
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39. For More Information
OSCARTM
• Web: www.xylem.com/treatment/us
• YouTube- www.youtube.com/user/SanitaireUS
• Phone: 1-414-365-2200
• Email: bulbul.ahmed@xyleminc.com
IQ SensorNet
• Web: www.ysi.com/wastewater
• Slideshare – www.slideshare.net/YSIinc
• YouTube – www.youtube.com/YSIinc
• Phone: 1-800-897-4151
• Email: info@ysi.com
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