Transcript Retro Fit Denit

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.
Presentation Outline
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Denitrification Process
Improvements at Genesee Water and Sanitation
District
Implementation Process
Questions
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Denitrification Process
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Denitrification Process
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Ammonia (NH3)
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In WW Process, Nitrogen bonds to Organic Molecules
to form Ammonia-Nitrogen (NH3 & NH4)
NH3 Converted to Nitrates in Aeration Process
Nitrates (NO3)
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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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Denitrification Process
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Denitrification
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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
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Attached Growth
Proprietary Processes
Single-Sludge Nitrification/Denitrification
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Single-Sludge Nitrification / Denitrification
•All modifications to existing nitrification facility
take place in aeration basin
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Anoxic Zone precedes Aeration
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Internal Water Recycle (400-500% of Influent Flow)
N2 Gas
RECYCLE
Influent
Effluent
Anoxic Zone
(Denitrification)
Aeration Zone
(Nitrification)
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Effect of Recycle on Nitrate Reduction
100
Nitrate Reduction (%)
90
80
70
60
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40
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10
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100
200
300
400
500
600
700
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Recycle Rate (%)
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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
NO3 Converted to N2
NH3 Converted to NO3
Zone
N2 Gas
RECYCLE
Effluent
Influent
Anoxic Zone
(Denitrification)
Aeration Zone
(Nitrification)
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Denitrification Calculations
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Conventional Nitrification Calculations Required
First
Denitrification Calculations, Solve For
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Recycle Ratio
Aerobic / Anoxic Residence Times
Aerobic / Anoxic Tank Volumes
Aerobic / Anoxic Ratio
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Genesee Water and Sanitation District
Wastewater Treatment Facility
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Project Background
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In Foothills West of Denver, Near I-70
District Serves 4,000+ People
Activated Sludge Facility
Discharge to Bear Creek
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Need for Project
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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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Existing Wastewater Process Schematic
Grit
Clarifier
Aeration
Basins
(typ.)
RAS
Clarifier
Clarifier
Sand
Filter
D
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S
C
H
A
R
G
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Chlorine
•Two Aeration Basins Operated in Parallel (0.25 MGD Capacity, Each)
•Three Secondary Clarifiers Operated in Series
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Existing Conditions
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Activated Sludge Facility
Design Flow 0.5 MGD
Actual Flows ≈ 0.25 MGD
Achieving Near Complete Nitrification
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Previous Average Conditions:
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Ammonia (mg/L)
Nitrates (mg/L)
Influent
25-40
< 0.5
Effluent
< 1.0
15-23
Limits
9-18.5
None
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Denitrification Calculation Results
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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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Denitrification Design Drawings
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Denitrification Design
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Baffle Wall in Aeration Basin
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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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Baffle Wall Installation
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Denitrification Design
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Submersible Mixer
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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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Mixer Installation
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Denitrification Design Drawings
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Denitrification Design Drawings
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Piping Design From Pump
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Denitrification Design
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Submersible Pump
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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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Pump Installation
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Denitrification Design
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Flow Measurement
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Flow Control
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Electromagnetic Flow Meter –
Endress + Hauser, Promag 50W
Ballcentric Plug Valve with Handwheel Gear – Pratt
Piping and Related Equipment
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C900 PVC Pipe, Fittings, and Glue
Ductile Iron Pipe, Fittings, and Hardware
Pipe Hangers, Support Brackets, and Hardware
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Flow and Piping Installation
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Denitrification Design
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Electrical Modifications
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Breakers, Starters, Controls
Installed for Pump, Meter, Mixer
Installed by Sub-Contractor
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Denitrification Installation
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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
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200 Man-Hours by District Staff
100 Man-Hours Electrical Sub-Contractor
300 Man-Hours Total
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Denitrification Results at Genesee
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Current Recycle Rate set at ≈ 230%
Effluent Nitrate Levels 3-5 mg/L (78% Reduction)
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Additional Benefits found at Genesee
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A Substantial Decrease in Added Alkalinity
Requirements has been Noted
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Better Settling and Clarity has been Noted in
Clarifiers
A Decrease in Aluminum Sulfate Usage has been
Noted
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Alkalinity is recovered in Recycled Water in Anoxic
Zone
Due to Increased Biological Phosphorous Uptake
More Effective Dewatering Process (Centrifuge)
Reduced Air Requirement in Aeration Basins
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Negatives to Denitrification found at Genesee
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Initial Electrical Consumption has increased 15%
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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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Total Costs
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$46,000 for One (0.25 MGD) Aeration Basin
Conversion
• Engineering
– $ 6,500
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Baffle Wall
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Pump & Equip.
Jib Crane & Trolley
Mixer & Equip.
Flow Meter
Plug Valve
Pipe, Supports, Etc.
Electrical
$ 6,200
– $ 4,900
– $ 1,400
– $10,300
– $ 2,900
– $ 500
– $ 3,300
– $ 9,900
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Design Implementation
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Design Implementation
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Determine Need
Establish Funding
Engineering Calculations / Design
Equipment / Materials Selection
Determine Resources Available
Installation
Financial / Chemical Changes
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Questions?
Zach Matyja
[email protected]
Jacobson Helgoth Consultants, Inc.
www.jhcinc.com
(303) 986-0733
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