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Use recovered glycol as a “feedstock” for reformulated aircraft deicing fluid (after meeting SAE AMS 1424 specifications), vehicle anti-freeze, aircraft lavatory fluid, coolants, coatings, paints, and

Recovered glycol may be reformulated as aircraft-deicing fluid after meeting all SAE AMS 1424 specifications. Glycol has many applications, including antifreeze in cooling and heating systems, in hydraulic brake fluids, and to deice airport runways and aircraft. Deicing involves the removal of frost, snow, or ice from aircraft surfaces or from paved areas including runways, taxiways, and gate areas. Four different types of aviation deicing fluids are identified in applicable standards, e.g. Society of Automotive AMS 1428 and AMS 1424 : 1. Type I fluids have a low viscosity, and provide only short term protection because they quickly flow off surfaces after use. They are typically sprayed on hot (130–180°F, 55-80°C) at high pressure to remove snow, ice, and frost. Usually they are dyed orange to aid in identification and application. 2. Type II fluids are pseudoplastic to prevent their immediate flow off aircraft surfaces. Typically the fluid film will remain in place until the aircraft attains approximately 100 knots. The high speeds required for viscosity breakdown means that this type of fluid is useful only for larger aircraft. The use of Type II fluids is diminishing in favor of Type IV. 3. Type III fluids’ viscosity lies in between that of Type I and Type II fluids. They are intended for use on slower aircrafts. 4. Type IV fluids meet the same AMS standards as Tier II fluids, but they provide a longer holdover time. They are typically dyed green to aid in the application of a consistent layer of fluid. The deicing of aircraft and airfield surfaces is required by the Federal Aviation Administration (FAA) to ensure the safety of passengers; however, when performed without discharge controls in place, airport deicing operations can result in environmental impacts. In addition to potential aquatic life and human health impacts from the toxicity of deicing chemicals, the biodegradation of glycol in surface waters can greatly impact water quality, including significant reduction in dissolved oxygen levels, leading to fish kills. Although disposal of deicing fluid through discharge to sewers is heavily regulated, this is not viewed as a sustainable solution. Deicing fluids may instead be recycled where suitable facilities exist. Special deicing pads may be installed with a recovery system that channels deicing fluid into large subterranean tanks. This mixture is then trucked to a recycling facility where it is cleaned in a series of mechanical and chemical refinement operations and then distilled to recover the basic glycol-based deicing agent. Additives are then introduced to produce regenerated deicing fluid.


Practice Information

Capital Cost: Very Expensive (>$500,000 US)
O&M Cost: High (>$100,000 US)
Payback Period: Short (2 – 5 years)
Staffing Requirements: High (>200 hours per month)
Reportability of Metrics: Quantitative metric with baseline for comparison practices and is already tracked
Maturity of Practice: Proven at multiple airports
Energy Reduction: Decreases energy consumption
Environmental Benefits: Significant, multiple environmental benefits
Social Benefits: Moderate social benefit

Airport Characteristics





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Case Studies

10/3/15

Detroit Metropolitan Airport - Wayne County Airport Authority

Spent Aircraft Deicing Fluid Runoff (SADR) is collected at Detroit Metropolitan Airport at four dedicated remote deicing pads. These deicing pads contain a total of 28 slots in which approximately 90% of all aircraft deicing at DTW occurs. Airlines are permitted to conduct event-deicing at gates under certain circumstances, and are permitted to conduct all “defrost” deicing at gates, as little collectable SADR is generated during this type of deicing. All SADR containing more than 2% propylene glycol (PG) is collected by a vendor under contract to the Wayne County Airport Authority. This SADR is hauled to an off-site recovery facility where it undergoes evaporation and distillation, yielding a 99.5+% pure industrial-grade PG that is suitable for use in all non-food, non-pharmaceutical products. Most PG recovered at DTW is used in the manufacture of paints and plastics. Between 250,000 and 500,000 gallons of pure PG is recovered from SADR each winter at DTW. Treating this quantity of SADR at one of the two Publically-Owned Treatment Works serving DTW would cost more than $2,000,000/yr. to treat, if this quantity of treatment capacity were available, which there is not. The cost to of the SADR to the WCAA is ~$250,000/yr, which includes all labor, transportation, and processing costs.


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