Retro-Fit Denitrification for Small Wastewater Treatment Facilities

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Retro-Fit Denitrification for Small Wastewater
Treatment Facilities
Tenth Annual Vail Professional Wastewater
Operators Seminar Friday, October 29,
2004 Zachary J. Matyja, E.I.T. Jacobson Helgoth
Consultants, Inc.
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Retro-Fit Denitrification Improvements

• Presentation Outline
• Denitrification Process
• Improvements at Genesee Water and Sanitation
  District
• Implementation Process
• Questions

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Retro-Fit Denitrification Improvements
Denitrification Process
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Retro-Fit Denitrification Improvements

• Denitrification Process
• Ammonia (NH3)
• In WW Process, Nitrogen bonds to Organic
  Molecules to form Ammonia-Nitrogen (NH3 NH4)
• NH3 Converted to Nitrates in Aeration Process
• Nitrates (NO3)
• Common in Natural Water
• Sources include Ag Runoff, Organic Matter,
  WWTF Discharges
• 10 mg/L Limit for Drinking Water
• Can Cause blue baby syndrome

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Retro-Fit Denitrification Improvements

• Denitrification Process
• Denitrification
• The biological conversion of nitrate-nitrogen
  to nitrogen gas (N2), nitrous oxide (N2O), and
  nitric oxide (NO)
• Occurs under anoxic conditions (no free oxygen
  available)
• Various Denitrification Processes
• Attached Growth
• Proprietary Processes
• Single-Sludge Nitrification/Denitrification

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Retro-Fit Denitrification Improvements

• Single-Sludge Nitrification / Denitrification
• All modifications to existing nitrification
  facility take place in aeration basin
• Anoxic Zone precedes Aeration
• Internal Water Recycle (400-500 of Influent
  Flow)

RECYCLE
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Retro-Fit Denitrification Improvements
Effect of Recycle on Nitrate Reduction
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Retro-Fit Denitrification Improvements

• Denitrification Chemistry
• Ammonia First Passes Through Anoxic Zone
• Ammonia is Converted to Nitrate in Aeration
  Zone
• Nitrate are Recycled to Anoxic Zone
• Nitrate are Converted to Nitrogen gas in Anoxic
  Zone

NO3 Converted to N2
NH3 Converted to NO3
N2 Gas
RECYCLE
Effluent
Influent
Anoxic Zone (Denitrification)
Aeration Zone (Nitrification)
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Retro-Fit Denitrification Improvements

• Denitrification Calculations
• Conventional Nitrification Calculations
  Required First
• Denitrification Calculations, Solve For
• Recycle Ratio
• Aerobic / Anoxic Residence Times
• Aerobic / Anoxic Tank Volumes
• Aerobic / Anoxic Ratio

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Retro-Fit Denitrification Improvements
Genesee Water and Sanitation District Wastewater
Treatment Facility
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Retro-Fit Denitrification Improvements

• Project Background
• In Foothills West of Denver, Near I-70
• District Serves 4,000 People
• Activated Sludge Facility
• Discharge to Bear Creek

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Retro-Fit Denitrification Improvements

• Need for Project
• 2002 Drought Low Flows in Bear Creek
• Bear Creek Water Quality for Downstream Users
• Potential District Water Quality Problems
• Potential Water Reuse
• Stay Ahead of the Game
• Potential Future Nitrate Effluent Regulations

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Retro-Fit Denitrification Improvements

• Existing Wastewater Process Schematic
• Two Aeration Basins Operated in Parallel (0.25
  MGD Capacity, Each)
• Three Secondary Clarifiers Operated in Series

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Retro-Fit Denitrification Improvements

• Existing Conditions
• Activated Sludge Facility
• Design Flow 0.5 MGD
• Actual Flows 0.25 MGD
• Achieving Near Complete Nitrification
• Previous Average Conditions
• Influent Effluent Limits
• Ammonia (mg/L) 25-40 lt 1.0 9-18.5
• Nitrates (mg/L) lt 0.5 15-23 None

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Retro-Fit Denitrification Improvements

• Denitrification Calculation Results
• Estimated Recycle Ratio 295
• Aerobic Residence Time Required 4.8 hours
• Anoxic Residence Time Required 2.0 hours
• Aerobic Tank Volume Fraction 71
• Anoxic Tank Volume Fraction 29

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Retro-Fit Denitrification Improvements
Denitrification Design Drawings
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Retro-Fit Denitrification Improvements

• Denitrification Design
• Baffle Wall in Aeration Basin
• Install Reinforced Flexible Baffle Curtain to
  Divide Basins
• Attached on all sides to Basin
• 3 x 4 Hole in Bottom Corner
• Furnished and Installed by Lange Containment
  Systems, Inc.

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Retro-Fit Denitrification Improvements
Baffle Wall Installation
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Retro-Fit Denitrification Improvements

• Denitrification Design
• Submersible Mixer
• Ensure Successful Mixing of Entire Anoxic Basin
• Primary purpose to keep all solids in
  suspension, and prevent settling in Anoxic
  Basin
• Evaluated Two Mixers, Flygt required two mixers
  to accomplish same mixing
• Selected USFilter EMU Uniprop

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Retro-Fit Denitrification Improvements
Mixer Installation
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Retro-Fit Denitrification Improvements
Denitrification Design Drawings
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Retro-Fit Denitrification Improvements

• Denitrification Design Drawings
• Piping Design From Pump

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Retro-Fit Denitrification Improvements

• Denitrification Design
• Submersible Pump
• Designed for 900 gpm, 10 TDH
• 5 hp, 1750 rpm, submersible motor
• Guide Rails to Raise Pump
• ITT Flygt Submersible Sewage Pump Purchased

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Retro-Fit Denitrification Improvements
Pump Installation
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Retro-Fit Denitrification Improvements

• Denitrification Design
• Flow Measurement
• Electromagnetic Flow Meter
• Endress Hauser, Promag 50W
• Flow Control
• Ballcentric Plug Valve with Handwheel Gear
  Pratt
• Piping and Related Equipment
• C900 PVC Pipe, Fittings, and Glue
• Ductile Iron Pipe, Fittings, and Hardware
• Pipe Hangers, Support Brackets, and Hardware

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Retro-Fit Denitrification Improvements
Flow and Piping Installation
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Retro-Fit Denitrification Improvements

• Denitrification Design
• Electrical Modifications
• Breakers, Starters, Controls
• Installed for Pump, Meter, Mixer
• Installed by Sub-Contractor

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Retro-Fit Denitrification Improvements

• Denitrification Installation
• Aeration Basin Offline
• Basin Power Washed
• Diffusers Removed / Plugged
• Baffle Wall Installed by Sub-Contractor
• Pump, Piping, Mixer Installed
• Electrical Hook-up by Sub-Contractor
• 200 Man-Hours by District Staff
• 100 Man-Hours Electrical Sub-Contractor
• 300 Man-Hours Total

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Retro-Fit Denitrification Improvements

• Denitrification Results at Genesee
• Current Recycle Rate set at 230
• Effluent Nitrate Levels 3-5 mg/L (78 Reduction)

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Retro-Fit Denitrification Improvements

• Additional Benefits found at Genesee
• A Substantial Decrease in Added Alkalinity
  Requirements has been Noted
• Alkalinity is recovered in Recycled Water in
  Anoxic Zone
• Better Settling and Clarity has been Noted in
  Clarifiers
• A Decrease in Aluminum Sulfate Usage has been
  Noted
• Due to Increased Biological Phosphorous Uptake
• More Effective Dewatering Process (Centrifuge)
• Reduced Air Requirement in Aeration Basins

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Retro-Fit Denitrification Improvements

• Negatives to Denitrification found at Genesee
• Initial Electrical Consumption has increased
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• From Pump, Mixer, and Meter Usage
• May Decrease because of Reduced Air
  Requirements
• Initial Operation Requirements to Determine
  Recycle Ratio
• More Frequent Monitoring for Filamentous
  Control in the Anoxic Zone

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Retro-Fit Denitrification Improvements

• Total Costs
• 46,000 for One (0.25 MGD) Aeration Basin
  Conversion
• Engineering 6,500
• Baffle Wall 6,200
• Pump Equip. 4,900
• Jib Crane Trolley 1,400
• Mixer Equip. 10,300
• Flow Meter 2,900
• Plug Valve 500
• Pipe, Supports, Etc. 3,300
• Electrical 9,900

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Retro-Fit Denitrification Improvements
Design Implementation
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Retro-Fit Denitrification Improvements

• Design Implementation
• Determine Need
• Establish Funding
• Engineering Calculations / Design
• Equipment / Materials Selection
• Determine Resources Available
• Installation
• Financial / Chemical Changes

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Retro-Fit Denitrification Improvements
Questions?
Zach Matyja zmatyja_at_jacobsonhelgoth.com Jacobson
Helgoth Consultants, Inc. www.jhcinc.com (303)
986-0733
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