The document discusses phosphorus (P) in water resources and treatment options for removing excess P. It notes that P is essential for life but excess amounts can cause algal growth. It outlines different sources of P in surface water and regulations for P limits in wastewater discharges. The main treatment options discussed are biological P removal, which uses microorganisms, and chemical P removal, which uses iron or aluminum additions. It emphasizes the importance of monitoring processes like orthophosphate, DO, and ORP to effectively remove P either biologically or chemically.

1. The Phosphorus Problem: Treatment Options and Process Monitoring Solutions
YSI WATER RESOURCE RECOVERY WEBINAR
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2. What is Phosphorus?
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Essential to life – all living organisms require it
•
No substitutes
•
Major component of fertilizer
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Creates nuisance conditions in excess
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Limiting nutrient in fresh water
•
High quality reserves are depleting
It’s more than just the letter ‘P’
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3. ‘P’ Promotes Growth of Algae
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Human health
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Environmental
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Economic
Excessive algal growth has many undesirable effects
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4. How Does ‘P’ Get Into Surface Water? 4
Diffuse sources
Point sources

5. Regulating ‘P’ in Point Source Discharges
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Technology-based limits (TBL)
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Typically 1.0 mg/L TP monthly average
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Total Maximum Daily Load (TMDL)
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Mass-based limit – as treated water flow ↑ concentration must ↓
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Water quality based emission limits (WQBEL)
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Numeric concentration limit to not cause adverse effects
3 types
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6. Status Of Numeric Nutrient Criteria (WQBEL)
Current
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7. Status Of Numeric Nutrient Criteria (WQBEL)
2016
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8. The Wisconsin Example
Adverse effects threshold depends on surface water type
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9. What Are You Going To Do?
Options for complying with ‘P’ limits
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Variance based on economic feasibility
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Water quality trading
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Trade with your neighbor
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Adaptive management
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Watershed based
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Operational changes / add chemical
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Improve treatment process
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Significant upgrades likely if WQBEL is < 0.6 mg/L
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Compliance schedule will extend 5+ years (not more than 9 years)
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10. Phosphorus Removal Treatment Options
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11. Terminology
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‘P’ = phosphorus
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TP = total phosphorus = particulate + dissolved phosphorus
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Orthophosphate = dissolved phosphorus = PO43-
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(E)BPR = (Enhanced) Biological Phosphorus Removal
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Oxic = aerobic = DO
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Anoxic = DO; NO3
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Anaerobic = DO; NO3
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12. How is ‘P’ Removed?
2 ways
1.
Biological
2.
Chemical
Basic concept: ‘P’ dissolved ‘P’ Particulate
‘P’

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

14. Effluent TP
Most WRRFs Are Not Designed to Remove ‘P’
Some ‘P’ removal occurs normally
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Soluble - P (Ortho-P)
Particulate P
Influent
Soluble - P
Particulate P
Secondary Effluent
TP
Biological Transformation
WAS

15. Bio or Chem P Removal
Most WRRFs Are Not Designed to Remove ‘P’
Some ‘P’ removal occurs normally
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Particulate P
Treated Effluent
Effluent TP
WAS
Soluble - P

16. Chemical Removal – How It Works
Addition of ferric or alum to water triggers a complex chain reaction
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Takacs, et al (2011), “Chemical P removal – from lab tests through model understanding to full-scale
Demonstration“, Influents, Water Environment Association of Ontario.
‘baby’ ferric hydroxide floc

17. Fe:P ratio (moles)
Dissolved P target, mg/L
Model Prediction
Plant Data
Surface complexation + Co-Precipitation + Other competing reactions Increased sludge production & alkalinity consumption
Relationship Between Dosage and Ortho P
Surface complexation Lower sludge production & alkalinity consumption

18. Chemical P Removal
Control strategies
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Pre-precipitation
Fe/ Al
‘P’

19. Chemical P Removal
Control strategies
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Simultaneous precipitation
Fe / Al
Fe / Al
‘P’

20. Chemical P Removal
Control strategies
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Post precipitation
‘P’
Fe / Al

21. Chemical P Removal
Control strategies
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Multiple dosing points

22. Why EBPR works? Energy Released by PHB oxidation is 24-36 times energy required for PHB storage
EBPR (Enhanced Biological Phosphorus Removal) Mechanism
Aerobic
Anaerobic
Waste Sludge Loaded with P
BOD (VFA) uptake & C (PHB) Storage P release
Feed condition Battery charging
Ortho- P
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PHB Oxidized
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Excess P Uptake
Starved condition Battery discharging

23. Anaerobic/Oxic (A/O) Process Configuration
RAS
Anaerobic
Aerobic
Net P Removal
Ortho-P
≥3 x Infl. Ortho-P
BOD
PHB Storage
BOD Oxidized
Concentrations in Bioreactor
Location in Bioreactor

24. Biological Phosphorus Removal
1.
Excess phosphorus
2.
Readily degradable carbon
3.
Cyclic anaerobic/oxic conditions
3 requirements
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25. Phosphorus Removal Monitoring Solutions
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26. Orthophosphate Cabinet Analyzers
Chemical or biological removal
•Wet chemistry
•4 main components:
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• Electronics
• Photometer & tubing
• Sample transport
• Reagent & solutions

27. Features of an Online Analyzer
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Low reagent consumption
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Suitable for outdoors
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Automatic calibration
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Integrated permeate pump
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Filter module
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28. Monitoring for Chemical P Removal
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Effluent monitoring
P 700 IQ

29. Monitoring for Chemical P Removal
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Feedback control
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Pre-precipitation
P 700 IQ

30. Monitoring for Chemical P Removal
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Feedback control
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Simultaneous precipitation
P 700 IQ
P 700 IQ

31. Monitoring for Chemical P Removal
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Feedback control
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Post precipitation
P 700 IQ

32. Monitoring for Chemical P Removal
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Feed forward control
P 700 IQ

33. Watertown, WI
Simultaneous precipitation

34. Chemical Cost Reduction
Analyzer installed in 2012
$0
$20,000
$40,000
$60,000
$80,000
$100,000
2011
2012
2013
2014 to
date
Ferric chloride costs
Annual expense
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3.0 mgd
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Limit = 1.0 mg TP /L (for now)
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Paid for itself in 1 year + other benefits
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Decreased sludge production
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35. EBPR Monitoring
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COD/BOD
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DO
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Nitrate
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TSS
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ORP
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Blanket depth
Everything is important!
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36. Biological ‘P’ Removal
Orthophosphate release and uptake
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‘P’ - release / anaerobic
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Adjust mixing
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Activate swing zone
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P 700 IQ

37. Biological ‘P’ Removal
Orthophosphate release and uptake
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‘P’ – uptake / oxic
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P 700 IQ

38. 0.02.04.06.08.010.00.0%20.0%40.0%60.0%80.0%100.0% Aeration Volume (% of Total Aeration Vol.) Ortho-P, mg/L 10-Sep-0711-Sep-0712-Sep-07
Courtesy City of Xenia
Dissolved Oxygen
‘P’ uptake is rapid when conditions are right

39. ‘P’ Uptake in Oxic Zone
Too low DO concentration limits performance
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Anaerobic
Aerobic
‘P’ Release
Infl. TP
Ortho-P
Location Along Bioreactor

40. ‘P’ Uptake in Oxic Zone
Too low DO concentration limits performance
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Anaerobic
Aerobic
‘P’ Release
Infl. TP
Ortho-P
Location Along Bioreactor
~55%
~30%

41. EBPR Monitoring
ORP
Reproduced G Olsson, M Nielsen, Z Yuan, A Lynggaard-Jensen, J-P Steyer (2005) Science & Technical Report No. 15, Instrumentation, Control, and Automation in Wastewater Systems, with permission from the copyright holders, IWA Publishing

42. ORP Control of Intermittent Aeration
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43. Biological ‘P’ Removal
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Too low – not enough time for PAO’s
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Too high
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Secondary release
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Competition
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Settleability
The role of SRT
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44. ‘P’ Removal and Sludge Settleability
Don’t let the ‘P’ get away!
10% P
6% P
8% P
4% P
2% P
Effluent TP = Dissolved P + Particulate P

45. Process Control Strategy for Achieving the Lowest Effluent TSS
SRT control and sludge blanket control
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Wahlberg, E. “What makes secondary clarifiers work”, WEFTEC 2013

46. Further reading
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Neethling, et al, Factors influencing the reliability of enhanced biological phosphorus removal, WERF report 01-CTS-3ASP, 2005.
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Jeyanayagam, S. and Husband, J., Chain Reaction: How chemical phosphorus removal really works, Water Environment & Technology, 2009.
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USEPA, Phosphorus Removal Design Manual (purple book), EPA/625/1- 87/001, 1987.
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Narayanan, B. et al, Critical role of aerobic uptake in biological phosphorus removal, WEFTEC proceedings, 2006.
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