glycol treatment at london’s heathrow airport
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Glycol Treatment at London’s Heathrow Airport. Scott Wallace and Mark Liner – Naturally Wallace Consulting David Cooper and Clodagh Murphy – ARM, Ltd. Russell Knight – British Airport Authority. Aircraft Deicing. - PowerPoint PPT PresentationTRANSCRIPT
Glycol Treatment at London’s Heathrow Airport
Scott Wallace and Mark Liner – Naturally Wallace Consulting
David Cooper and Clodagh Murphy – ARM, Ltd.
Russell Knight – British Airport Authority
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
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
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
Overview of pollution control at Heathrow
Spout Lane Lagoon
Mayfield Farm main reservoir
Causeway Nature Reserve – part of Eastern Balancing Reservoirs
Clockhouse Lane Pit – Cable 1 part of Princes ski club
The Case for Upgrading Mayfield Farm
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Aircraft Pavement• Relatively mild winters post original construction (change in design basis)
• More stringent consent limits
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Aircraft Pavement
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Aircraft Pavement
Buffalo Niagara International Airport• Heavy snow loads in winter
• Airfield operations are heavily dependent on effective deicing operations
Treatability Testing
• Measure glycol degradation in both warm and cold temperatures
• With and without aeration
Aerated rate coefficients, low temperature runs
Run
Average CBOD5 (mg/L)
k2TIS(d-1)InfluentEffluent
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
PG degradation without aeration…
Run
Average CBOD5 (mg/L)
k4TIS(d-1)Influent Effluent
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
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!
Buffalo – Completed Treatment System
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)
Full- ScaleTrialWinter 2009/10
Effluent
Blower
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BED A BED B BED C
Effluent
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Effluent
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BED A BED B BED C
Mayfield Farm Treatment WorksOriginal System Re-engineered System
Horizontal subsurface
flow wetlands
Balancing Reservoir
Floating treatment wetlands
Primary Treatment
Secondary Treatment
Aerated Wetland Layout
Aeration Tubing Plow
Tertiary Treatment
Thank You for Your Attention