38    SPENT AIRCRAFT DEICING FLUID AS
EXTERNAL CARBON SOURCE FOR
DENITRIFICATION OF MUNICIPAL WASTEWATER:
FROM WASTE PROBLEM TO BENEFICIAL USE
B jorn Rusten, Senior Scientist and Partner
Asgeir Wien, Environmental Engineer
Aquateam - Norwegian Water Technology Centre A/S,
Etterstad, 0604 Oslo, Norway
Jostein Skjefstad, Manager for Water and Sewage Works
Ullensaker Municipality, Norway
INTRODUCTION
Use of deicing chemicals at airports is necessary to ensure passenger safety during winter operation. Traditional aircraft and runway deicing and anti-icing procedures create runoff that locally causes major pollution problems. The use of deicing and anti-icing chemicals is expected to
increase, and it is therefore important to find alternative technologies and strategies that will
minimize the environmental impacts of deicing activities.1 Treating airport storm water runoff at
a nearby municipal wastewater treatment plant (WWTP) is a possibility. Normally, however, the
WWTP is not designed to handle the very high organic loads from deicing chemicals, and this
may cause unstable operation and poor effluent quality.2"4
In connection with the construction of the new Oslo airport in Norway, a new WWTP serving
the airport and the surrounding communities has to be built as well. This provided a unique opportunity to plan for an environmentally sound handling of deicing chemicals. One novel idea,
which will be the main focus of this chapter, is to use the spent aircraft deicing fluid (ADF) as an
external carbon source for denitrification at the municipal WWTP.
USE AND HANDLING OF DEICING FLUIDS AT THE NEW AIRPORT
Runway Deicing
A potassium acetate-based deicing fluid, with the commercial name Clearway, will be used for
runway deicing. Potassium acetate is a lesser polluting substitute for urea, which has been the
commonly used deicer for runways.1 At the new Oslo airport, runoff from the runway will be
collected and treated in soil infiltration systems.
Aircraft Deicing
Deicing Chemicals
Only ethylene or propylene glycol-based aircraft deicing fluids are approved by the aviation
authorities. Propylene glycol is less toxic than ethylene glycol.5
Monopropylene glycol (MPG) is used for aircraft deicing at the old Oslo airport, and will also
be used at the new one. Specifications supplied from the manufacturer,6 are shown in Table I.
Type I is a relatively thin liquid that is usually heated and used to remove ice and snow from
wings and fuselages. Type II is a high viscosity fluid typically used for anti-icing because it
51st Purdue Industrial Waste Conference Proceedings, 1996, Ann Arbor Press, Inc., Chelsea, Michigan 48118.
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