1. 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

2. Aircraft Deicing Deicing fluids include ethylene glycol (EG), propylene glycol (PG) and diethylene glycol (DEG). Commonly used as a 50% concentrate form (CBOD 5 approximately 200,000 mg/L). Runoff can contain over 20,000 mg/L at 1 o C New environmental regulations are requiring treatment of deicing runoff. Major challenge for conventional treatment plants

3. 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

4. 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

5. 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

6. The Case for Upgrading Mayfield Farm Relatively mild winters post original construction (change in design basis) More stringent consent limits

7. Buffalo Niagara International Airport Heavy snow loads in winter Airfield operations are heavily dependent on effective deicing operations

8. Treatability Testing Measure glycol degradation in both warm and cold temperatures With and without aeration

9. Aerated rate coefficients, low temperature runs Run Average CBOD 5 (mg/L) k 2TIS (d -1 ) Influent Effluent A648.826.54.81 B679.321.05.72 C325.010.35.63 D694.023.55.41 Average5.39

10. PG degradation without aeration… Run Average CBOD 5 (mg/L) k 4TIS (d -1 ) Influent Effluent A542.3212.30.68 B257.0119.00.27 C177.029.00.73 D129.533.50.51 Average0.55

11. 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!

14. Buffalo – Completed Treatment System

17. Comparing Heathrow and Buffalo wetlands Heathrow (prior to upgrade) Buffalo Design COD load590 kg/d4540 kg/d Area2.08 ha1.67 ha Bed Volume12480 m 3 28370 m 3 COD Loading47 g/m 3 -d160 g/m 3 -d (clogging limited) AerationNone750 kW Oxygen Transfer2.4 – 7.7 g/m 2 -d270 g/m 2 -d COD Removal4 – 13 g/m 3 -dUp to 160 g/m 3 -d Flow PathHorizontalVertical (due to high load)

18. Full- ScaleTrial Winter 2009/10

20. 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

21. 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)

22. Mayfield Farm Treatment Works Original System Re-engineered System Horizontal subsurface flow wetlands Balancing Reservoir Floating treatment wetlands

23. Primary Treatment

24. Secondary Treatment

25. Aerated Wetland Layout

26. Aeration Tubing Plow

27. Tertiary Treatment

28. Thank You for Your Attention