Glycol Treatment for Aircraft Deicing

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Glycol Treatment for Aircraft Deicing
Scott Wallace and Mark Liner Naturally Wallace
Consulting David Cooper and Clodagh Murphy ARM,
Ltd. Russell Knight British Airport Authority
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Aircraft Deicing

• Deicing fluids include ethylene glycol (EG),
  propylene glycol (PG) and diethylene glycol
  (DEG).
• Commonly used as a 50 concentrate form (CBOD5
  approximately 200,000 mg/L).
• Runoff can contain over 20,000 mg/L at 1 oC
• New environmental regulations are requiring
  treatment of deicing runoff.
• Major challenge for conventional treatment plants

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Deicing Runoff Treatment Options

• Anaerobic Digestion (biogas)
• Shock loadings, limited net biogas
• Mechanical Treatment (activated sludge, MBRs)
• Shock loadings, energy intensive
• Discharge to Regional Sewer
• Long-term concerns over cost and capacity
• Passive (ponds and open-water wetlands)
• Land intensive, BASH
• Subsurface Flow Treatment Wetlands
• No water exposed, land intensive

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Overview of pollution control at Heathrow
Causeway Nature Reserve part of Eastern
Balancing Reservoirs
Spout Lane Lagoon
Clockhouse Lane Pit Cable 1 part of Princes ski
club
Mayfield Farm main reservoir
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Original Heathrow Constructed Wetlands

• Papers published in 2001 and 2004
• 12 reed beds, total area 2.08 ha
• Design flow rate 40 L/s influent COD of 170 mg/L
• Removal efficiency of 30-68, 24-77 kg/ha-d

Richter et al. 2004
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The Case for Upgrading Mayfield Farm

• Relatively mild winters post original
  construction (change in design basis)
• More stringent consent limits

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Buffalo Niagara International Airport

• Heavy snow loads in winter
• Airfield operations are heavily dependent on
  effective deicing operations

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Treatability Testing

• Measure glycol degradation in both warm and cold
  temperatures
• With and without aeration

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Aerated rate coefficients, low temperature runs
Run Average CBOD5 (mg/L) Average CBOD5 (mg/L) k2TIS(d-1)
Run Influent Effluent k2TIS(d-1)
A 648.8 26.5 4.81
B 679.3 21.0 5.72
C 325.0 10.3 5.63
D 694.0 23.5 5.41
Average 5.39
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PG degradation without aeration
Run Average CBOD5 (mg/L) Average CBOD5 (mg/L) k4TIS(d-1)
Run Influent Effluent k4TIS(d-1)
A 542.3 212.3 0.68
B 257.0 119.0 0.27
C 177.0 29.0 0.73
D 129.5 33.5 0.51
Average 0.55
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Comparing Treatment Effectiveness

• Aerated rate coefficient 5.30 d-1
• Non-aerated rate coefficient 0.55 d-1
• An aerated wetland is 10X more effective in
  treating glycol!

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Buffalo Completed Treatment System
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Comparing Heathrow and Buffalo wetlands
Heathrow (prior to upgrade) Buffalo
Design COD load 590 kg/d 4540 kg/d
Area 2.08 ha 1.67 ha
Bed Volume 12480 m3 28370 m3
COD Loading 47 g/m3-d 160 g/m3-d (clogging limited)
Aeration None 750 kW
Oxygen Transfer 2.4 7.7 g/m2-d 270 g/m2-d
COD Removal 4 13 g/m3-d Up to 160 g/m3-d
Flow Path Horizontal Vertical (due to high load)
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Full- ScaleTrialWinter 2009/10
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Aims and objectives of quick wins

• Improve environmental outcomes
• Improve regulator perception
• Reduce unplanned OPEX
• Maintain biodiversity during construction and
  operation
• Out of scope
• Long term storage solution

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Scope of Heathrow Stormwater Quick Wins

• Mayfield Farm
• Treatment Upgrades to Floating Reedbeds,
  Balancing Lagoon, Horizontal Reedbeds, nutrient
  dosing facility, power and controls
• Aeration to Main Reservoir
• Eastern Balancing Reservoir
• Aeration to upper pond lower pond including
  power and controls
• Clock House Lane Contingency
• Aeration including power and controls
• Spout Lane
• The ability to increase pumping to foul from
  50l/s to 100l/s, improve reliability and reduce
  cost (subject to TWU approval)

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Mayfield Farm Treatment Works
Original System
Re-engineered System
Horizontal subsurface flow wetlands
Balancing Reservoir
Floating treatment wetlands
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Primary Treatment
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Secondary Treatment
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Aerated Wetland Layout
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Aeration Tubing Plow
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Tertiary Treatment
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Thank You for Your Attention