This presentation is about online sensors for sidestream treatment of centrate in wastewater. This is a description of a sensor evaluation performed at Los Angeles County Sanitation District JWPCP during a pilot study of centrate treatment.

1. Online Sensors for
Sidestream Treatment of Centrate –
A Sensor Evaluation and Lessons
Learned

2. Acknowledgements
• Sanitation Districts of Los Angeles County
• Robert Morton, Supervising Engineer
• Wastewater Research Section
• JWPCP Laboratory
• YSI, a Xylem brand
• Herb Fancher
• Uli Franke
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3. Presenters
• Rob Smith
• YSI, a Xylem brand
• Applications Engineer
• Online monitoring
• P.E., BCEE, Ph.D.
• Nick Smal
• Sanitation District of
LA County
• Project Engineer
• P.E.
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4. Topics
• The problem with centrate nitrogen
• Evolution of sidestream treatment
• Introducing the LA County Sanitation District
JWPCP
• Centrate treatment pilot plant
• Online nitrogen monitoring results
• Summary
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5. The Problem with
Centrate Nitrogen
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6. Fate of Nitrogen Removed from Wastewater
For every 1 mil. gal. of water treated:
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Primary
Settler
Primary Sludge
(30 lbs. N)
Waste Activated Sludge
(140 lbs. N)
330 lbs. N

7. Anaerobic Digestion Releases Captured
Nitrogen
Ammonia is recycled to main-stream in centrate
7
Primary
Settler
Sludge
Thickener
Anaerobic
Digester
Sludge
DewateringCake
N = 300 to 1,000 mg/L
~10% of influent load

8. N x 1
Imported Sludge
Increases the mass of nitrogen in centrate
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Primary
Settler
Sludge
Thickener
Anaerobic
Digester
Sludge
DewateringCake

9. Imported Sludge
Increases the mass of nitrogen in centrate
9
Primary
Settler
Sludge
Thickener
Anaerobic
Digester
Sludge
DewateringCake
N x 2

10. Imported Sludge
Increases the mass of nitrogen in centrate
10
Primary
Settler
Sludge
Thickener
Anaerobic
Digester
Sludge
DewateringCake
N x 3

11. Solids Pre-Treatment
Increases the mass & concentration of nitrogen in centrate
11
Primary
Settler
Sludge
Thickener
Anaerobic
Digester
Sludge
DewateringCake
N = 1,500 to 3,000 mg/L

12. Centrate Handling Alternatives
• Do Nothing
• Export
• Attenuate
• Treat
• Integrated treatment
• Separate treatment
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13. Why Sidestream Treatment?
• Anaerobic digestion/centrate dewatering
• Medium to Very Large
• Nutrient limits
• Regional solids handling facilities
• Sustainability
Characteristics of utilities with most to gain:
13

14. Evolution of Side-
Stream Treatment
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15. Integrated Treatment – In-Line
RAS
f
1 - f
15

16. Integrated Treatment – Off-Line
Nitrate to Headworks
16

17. 1 mole Ammonia
(NH3 / NH4
+)
1 mole Nitrite
(NO2
-)
1 mole Nitrate
(NO3
-)
1 mole Nitrite
(NO2
-)
1/2 mole Nitrogen gas
(N2)
75% O2
25% O2
40% Carbon
60% Carbon
Nitrification /
Denitrification
Aerobic Anoxic
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18. Separate Treatment – SHARON
Complete Mix
Plug Flow
Concentric
MeOH
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Centrate
Centrate

19. 1 mole Ammonia
(NH3 / NH4
+)
1 mole Nitrite
(NO2
-)
1 mole Nitrite
(NO2
-)
1/2 mole Nitrogen gas
(N2)
75% O2
60% Carbon
Nitritation /
Denitritation
Aerobic Anoxic
19

20. Separate Treatment - Deammonification
• Anaerobic (no oxygen)
• Autotrophic (no organic C)
• Requires ammonium + nitrite
• Very slow growing
• Nitrite toxicity?
Anammox reaction

21. 37.5% O2
1/2 mole Ammonia
(NH3 / NH4
+)
1/2 mole Nitrite
(NO2
-)
1/2 mole Nitrogen gas
(N2)
Aerobic Anoxic
Deammonification
Anaerobic
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22. Major Deammonification Technologies
3 commercial technologies • SBR (DEMON, Clear
Green)
• Granular sludge
(ANAMMOX)
• MBBR (ANITA Mox)

23. Sanitation District of Los
Angeles County
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25. Joint Water Pollution Control Plant
N
PrimaryAnaerobic
Digesters
Secondary
Solids
Processing

26. JWPCP Overview
NaOCl

27. Centrate Treatment Pilot
Plant - MBBR
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28. Sidestream Treatment
Nitrogen Removal
ANAMMX
ANITA Mox
System

29. Centrate Water Quality – Grab samples
Parameters Unit
Pre-DAF
8/21/2013-
11/15/2013
Post-DAF
5/20/2013-
08/20/2013
Nitrogen
TKN mg N/L 585 469
NH4-N+ mg N/L 573 463
Organic matter
COD mg/L 345 181
sCOD mg/L 136 128
BOD mg/L 49 21
TSS mg/L 201 64
Alkalinity mg CaCO3/L 2290 1930

30. Pilot System
ANITA Mox / Veolia
• Drum screen - 60 µm mesh panels
• Feed tank (equalization)
• Reactor
• Volume ~ 950 gal
• Media type: AnoxKaldnes K5
(800m2/m3)
• Media Fill: 47%
• Seed Ratio: 100%

31. Pilot System Operation
• Instrumentation and Control
• DO/Aeration
• Feed Flow
• pH
• Temperature
Feed Pump
Reactor
Air Mass Flow
Controller
DO pH
Flow
Meter
Plant Air
Feed Tank

32. Why Online Monitoring
Over a 25% Reduce in weekly laboratory demand
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Category Parameter Influent Effluent
tCOD W W
sCOD W W
tBOD W W
sBOD W W
TSS D D
VSS D D
TKN W W
NH4-N D D
NO2-N W D
NO3-N W D
PO4-P W --
Alkalinity D D
Biomass -- W
pH D Online
DO -- Online
Temperature -- Online
Others
Organics
Solids
Nitrogen
Category Parameter Influent Effluent
tCOD W Online
sCOD W Online
tBOD W Online
sBOD W Online
TSS D D
VSS D D
TKN W Online
NH4-N D Online
NO2-N W Online
NO3-N W Online
PO4-P W --
Alkalinity D D
Biomass -- W
pH D Online
DO -- Online
Temperature -- Online
Organics
Solids
Nitrogen
Others
91 Samples 65 Samples

33. Ammonium (NH4
+) & nitrate (NO3
-)
Ion selective electrodes (ISE) • Potentiometric (like
pH)
• Requires calibration at
commissioning
(matrix adjustment)
• More potential for drift
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34. Detector
Lamp
meas.channel
ref.-channel
Nitrite (NO2
-) & Nitrate (NO3
-)
UV spectral sensor for nitrate & nitrite • Optical
• 256 wavelengths
scanned
• Factory calibrated
(Application specific)
• Built-in ultrasonic
cleaning
• Much lower potential
for drift
• Quadruple sensor
with COD/BOD

35. Monitoring Results
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36. How Nitrogen Measurements Can Be Used
to Better Control the Process
• Ammonia (NH3-N)
• Check of feed rate loop
• Above 200 mg / L– Reduce feed
• Nitrate (NO3-N)
• Check of DO loop
• Above 35 mg / L – Reduce DO
• Nitrite (NO2-N)
• Toxicity / Check of DO loop
• Above 8 mg / L – Depends on NH4 and
NO3 concentrations36

37. 1/2 mole Ammonia
(NH3 / NH4
+)
1/2 mole Nitrite
(NO2
-)
1/2 mole Nitrogen gas
(N2)
37.5% O2
Aerobic Anoxic
Deammonification
Anaerobic
37
(AOB) Anammox
NO3
-
11% to nitrate

38. 1/2 mole Ammonia
(NH3 / NH4
+)
1/2 mole Nitrite
(NO2
-)
1/2 mole Nitrogen gas
(N2)
37.5% O2
Aerobic Anoxic
Deammonification
Anaerobic
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(AOB) Anammox
NO3
-
> 11% - NOB

39. Great
Nitrate
ISE
39

40. Nitrate Monitoring
“Very impressed with nitrate ISE” • Easiest to use
• Calibrate
• Clean (air
cleaning)
• 32/33 within 20% of
lab photometer
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41. Nitrate Monitoring
UV
41
User calibration

42. Nitrate Monitoring
Not as good as nitrate ISE • Cleaning more
tedious
• No air cleaning
• 28/41 within 20% of
lab photometer
• Online measurement
tended to
underestimate
• Better calibration
needed (more points)
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43. Good
Ammonium ISE trending
43
Stress testing

44. Ammonium Monitoring
• Good trending during
stress testing
• 19/34 within 20% of
lab photometer
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45. Bad to Good (with user calibration)
Nitrite UV
45
User calibrationOverestimate

46. Nitrite Monitoring
After user calibration • Most interested in
monitoring nitrite
• Toxicity
concerns
• 12/24 within 20% of
lab photometer
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47. Why Is It So Difficult to Measure Nitrite?
Overlapping spectra • Lots of wavelengths
required (256)
• High resolution (0.74
nm)
• Compensation for COD
and turbidity important
• Application specific
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wavelength [nm]
Intensity

48. Pilot Study/Sensor
Evaluation Summary
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49. LA County Take-Aways
• Sensor accuracy satisfactory for the short
duration of the trial.
• Very pleased with the nitrate ISE
• Sensors provided real time observation of the
process – better understanding of dynamics.
• Nitrite toxicity not as critical to process
• Nitrate/ammonium maybe more critical
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50. YSI Take-Aways
• The human is the most important factor
• Objective
• Puts in time when needed
• Stay close to the customer
• Training
• Configuration
• Intervention
• Data evaluation reveals successes and how
things that could be done better
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51. Rob Smith
rsmith@ysi.com
Questions and comments very welcome
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