FEATURE
Airport Pollution Prevention Takes Off Airports and airlines are under increasing pressure to prevent chemical runoff from polluting local waters. KELLYN S. BETTS elta Airlines' tiny outpost at Milwaukee's General Mitchell International Airport only operates seven flights a day, but its new state-of-the-art technology for de-icing planes belies its size. Since January, the airline has been using less than one-third of the chemicals usually required to safely send planes aloft in freezing weather. By the end of April, Delta expected to have made a final decision about whether to clear the pollution-preventing technology for travel to other airports. Delta's alternative de-icing system is one of more than a dozen new technologies being developed to help airports cope with the water pollution caused by airplane de-icing chemicals, said Craig Richardson, a consultant for the Clean Airports Initiative, a nonprofit group in Denver, Colo. The Federal Aviation Administration expects worldwide air travel to increase by 5.8% annually between 1998 and 2008 (2), and Richardson is compiling a study detailing the environmental and land-use issues associated with airport growth. At present, airplane de-icing chemicals are not regulated, although the two most popular airplane deicing fluids, which are ethylene glycol- and propylene glycol-based, are known to cause aquatic toxicity. Ethylene glycol also has mammalian toxicity. In addition, new evidence indicates that some of the proprietary chemicals added to the glycols to inhibit corrosion and retard flammability also may be toxic. Although neither of the two main de-icer's vendors— Union Carbide and Arco Chemical—will divulge the chemical composition of their additives, Devon Cancilia, assistant professor at Western Washington University's Huxley College of Environmental Studies in Bellingham, Wash., determined that tolyltriazoles are used as corrosion inhibitors in virtually all antiicing formulations (2).
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Cancilla recently discovered high concentrations of these chemicals, which he characterized as being much more toxic than ethylene glycol alone, in subsurface water near a major North American airport (2). Other groups have shown that de-icing solutions have a broad range of toxicity (3), he said. "The limits for how much de-icing fluid could be discharged were set based on the toxicity of ethylene and propylene glycol, not the additives," he explained, noting that the tolyltriazoles would not be found with typical EPA testing methods. The finding could further provoke organizations like the Natural Resources Defense Council (NRDC) that are already agitating for de-icing chemical regulation. On the basis of glycol discharges alone, NRDC sued Baltimore-Washington International and Chicago's O'Hare airports for polluting local waters. Airports in Des Moines, Iowa, Westchester County, N.Y., Wilmington, Ohio, and Denver, Colo., have documented de-icing pollution problems, said Richardson. "It's a growing issue," summarized Steve Howards, executive director of the Clean Airports Initiative. Evidence mounts De-icing large commercial aircraft demands 500-1000 gallons of de-icing fluid on average (4). A medium-sized airport may use over 264,000 gallons of the fluid over the entire winter season, said Clark Norton, environmental manager for Calgary International Airport. Evidence that some of these deicing chemicals make their way into local water bodies has been mounting since the mid-1990s when EPA's National Pollution Discharge Elimination System (NPDES) began forcing airports and their surrounding municipalities to quantify their runoff, said John Lengel, an environmental engineer specializing in transportation for Camp, Dresser, and McKee, an international environmental consulting firm. © 1999 American Chemical Society
Spurred by a different NRDC lawsuit, EPA is collecting data to determine whether de-icing fluid should be regulated on a national scale, said Shari Zuskin, project manager for EPA's airport de-icing study. Since the study began in early 1998, the number of airports and airlines implementing programs to attack de-icing runoff has "really been increasing," Zuskin said. Depending upon the tack that airports take, combating de-icing runoff has the potential to be a "win-win situation," Howards said. "This is a real good example of where being environmentally conscious can actually Although the evidence of environmental harm from aircraft de-icing chemical runoff is mountsave them money," he added. For ex- ing, the number of technologies available to mitigate their effects is also increasing. (Courtesy ample, at Milwaukee's General Mitch- Associated Press) ell Airport, the amount of "type 1" deicing fluid—the de-icing material sprayed in the greatest quantities—used per plane has was damaged during the higher-pressure tests in the dropped from 120 to 25 gallons, said Brian Knusta, su- previous year. Since lowering the pressure, howpervisor and environmental coordinator for Delta Air- ever, he said that the airline has been pleased with lines. Because the airline pays approximately $5 for each the results. Knusta expressed confidence that Delta gallon of glycol it uses, as well as spending an addi- would adopt the technique but stressed that the airtional $10 per gallon in airport disposal fees, the sav- line needed hard data on the technology's perforings ultimately could be substantial. mance in wet, heavy snows and ice storms— The de-icing system that Delta is testing was the weather that normally hits Wisconsin in early spring— brainchild of scientists at Allied Signal Aerospace. Re- before a final decision could be made. searchers at Premier Engineering, one of the naOther similar pollution-preventing technologies are tion's top three manufacturers of aircraft de-icing currently being readied for market. Premier's two main equipment, developed it into a product. The tech- competitors, FMC Aerospace and Global Ground Supnology capitalizes on a specially designed nozzle that port Equipment, are developing air-assisted glycol injects a relatively low volume of glycol into the cen- sprayers. Infrared Technologies is taking a different apter of a high-pressure air flow, allowing the heated proach with Ice-Cat, a mobile flameless gas catalytic air to aid in de-icing. "It's the only technology to in- heater, which it claims can reduce ethylene glycol usject glycol into the air to make a one-step de-icing age by up to 90%; unfortunately, the company has yet process," said Jerry Derusha, Premier's president. Ac- to convince an airline to test the Ice-Cat. "Until an enknowledging that his two main competitors also are vironmental mandate comes down that requires airdeveloping "air-assisted" processes to reduce glycol ports to reduce their use of glycol, they never will," said use, he stressed that the superior speed with which Ward Brasses, Infrared's vice president and general manhis company's new process can de-ice a plane gives ager. However, a Buffalo airport is trying out a stationit an edge in the fast-paced airline business. Pre- ary version of this catalytic heating technology called mier's technology also is being tested at the Naval Air Infratek, made by Process Technologies, to de-ice Station in Brunswick, Maine, he noted. smaller aircraft inside an airplane hangar, rather than At General Mitchell Airport, the 70% reduction in transporting it by truck to the plane. type 1 glycol de-icing fluid that Delta achieved by usFurther out on the pollution-prevention horizon ing Premier's technology during this year's first 42 are alternative de-icing formulations like UltraTreat"snow and frost events" gready exceeded Delta's re- ment, a biodegradable anti-ice fluid being develquired contribution to the reduction targets set by oped by Union Carbide, and other pollutionMilwaukee County's NPDES permits, said Greg Failey, reducing mixes devised by the National Aeronautical the county's environmental manager. Those perand Space Administration, said Richardson. Some airmits challenged the airport to reduce its de-icing gly- lines are investigating the possibility of installing eleccol discharges by 42% because they go direcdy from trically heated panels in aircraft wings, while oththe county's storm sewer system into a channel that ers are looking into the feasibility of using ice drains into a Lake Michigan estuary. The U.S. Geodetection systems. logical Survey is currently finishing up a study of airplane de-icing runoff at the airport. The recapture/treatment front In addition to pollution-preventing technologies, 800-mph spray there are two other strategies airports can use to cut Although the glycol-laden air ejected from Pre- down their glycol discharges, Zuskin explained. They mier's spray guns hits the aircraft at 800 mph, the can embrace technologies for recovering and recyplanes have thus far proved impervious to the imcling the glycol, or they can somehow treat their runpact, Knusta said. He admitted that an aircraft wing off before discharging it. MAY 1 1
