v>EPA
United States
Environmental Protection
Agency
Office of Water
Washington, D.C.
EPA 832-F-99-043
September 1999
Storm Water
Technology Fact Sheet
Airplane Deicing Fluid Recovery Systems
DESCRIPTION
Under the guidance of Section 402 of the Clean
Water Act, the Federal Aviation Administration has
approved the use of ethylene glycol and propylene
glycol as chemical deicers. The recovery of spent
ethylene glycol or propylene glycol from industrial
processes is accomplished by a three-stage process
typically consisting of primary filtration,
contaminant removal via ion exchange or
nanofiltration, and distillation, as shown in Figure 1.
The process technologies involved in glycol
recovery have been proven in other industries and
are now being applied to spent airplane deicing fluid
(ADF.)
Primary filtration, which is defined as the removal of
solids greater than 10 microns in size, is intended to
remove entrained suspended solids from the used
ADF. The suspended solids must be removed to
avoid plugging of downstream equipment and heat
exchangers. Primary filters employed by ADF
systems are either polypropylene cartridges or bag
filters.
Contaminant removal can occur through ion
exchange or nanofiltration. Ion exchange removes
dissolved solids such as chlorides and sulfates from
an aqueous solution by passing the wastewater
through a solid material (called ion exchange resin).
This exchange process removes specific ions, and
returns an equivalent number of desirable ions from
the resin. Another approach to contaminant removal
is nanofiltration. Nanofiltration systems are
pressure-driven membrane operations that use
porous membranes to remove colloidal material and
polymeric additives with molecular weights in
excess of 500 from the spent ADF. The need to
remove polymer additives is dictated by the
specifications of the end user of the recovered ADF
ION EXCHANGE
(REMOVAL OF DISSOLVED SOLIDS)
CARTRIDGE FILTER
WASTEWATER
DILUTE GLYCOL
FROM AIRPORT
COLLECTION
SYSTEM
(>15% GLYCOL)
PCTATED BY CONTAMINANTS AND
END USER SPECIFICATIONS)
PRIMARY FILTRATION
(REMOVAL OF PARTICLES
LARGER THAN 10 MICRONS)
Note: Spent cartridge and nanolilter elements
must be disposed of as solid waste
. CONCENTRATED
GLYCOL
(CONCENTRATION DICTATED
BY END USER)
TWO STAGE-DISTILLATION
(REMOVAL OF WATER)
(REMOVAL OF POLYMERS)
Source: ENSR Consulting and Engineering, 1993.
FIGURE 1 TYPICAL AIRPLANE DEICING FLUID RECOVERY SYSTEM
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product.
The key process step in the overall ADF recycling
system is distillation. Distillation is defined as the
separation of more volatile materials (in this case,
water) from less volatile materials (glycol) through
a process of vaporization and condensation.
Distillation is capable of recovering volatiles with
little degradation of the recovered product. This is
very advantageous in situations where the recovered
product can be sold or recycled. Product purity of
any desired level can theoretically be obtained by
distillation; however, in some cases the processing
costs may be prohibitive. In most ADF applications,
the separation of water from either a water-ethyl ene
glycol or a water-propylene glycol mixture of ADF
employs a two stage distillation process. This will
typically remove enough water to produce a
recovered ADF with a minimum 50 percent glycol
content. The requirement glycol concentration is
dictated by the specifications of the end user of the
recovered ADF product.
The details of the distillation processes employed by
specific vendors are proprietary. Design variables
include temperature, distillation column design
(number of stages, type of packing, size) and reflux
ratio. Batch distillation systems are generally
employed due to the variation in the composition of
the influent and the irregular supply of the feed.
Secondary filtration and ion-exchange stages vary
with the quality of the influent feed and the
specifications of the end-user. The temperature of
distillation also varies between ethylene glycol and
propylene glycol recovery applications.
APPLICABILITY
Ethylene glycol or propylene glycol recovery
systems are generally applicable at any airport that
collects ADF with a minimum concentration of
approximately 15 percent glycol. Spent ADF
mixtures with lower glycol content are generally
impractical to recover via distillation, without
expensive preconcentration steps such as reverse
osmosis. Dilute streams are typically discharged to
municipal wastewater treatment plants (if
permitted), treated by oxidation to destroy the
organics prior to direct discharge, or hauled away
by a chemical waste contractor. A number of other
BMPs, such as water quality inlets and oil\water
separators, are being tested to demonstrate their
ability and reliability to concentrate dilute streams of
spent ADF.
While the basic technologies used to recycle
ethylene glycol and propylene glycol are well
established, actual operating experience in recycling
airplane deicing fluids is limited. To date, there is
only one on-site application of ADF recovery
operating in the United States. This is a pilot-scale
operation conducted for Continental Airlines at the
Denver International Airport. Another pilot-scale
ADF operation is currently being conducted in
Canada at the L.B. Pearson Airport in Toronto. A
recovery system is also being proposed for the St.
Louis, Missouri, Airport, but this system is currently
not in operation. There are also three ADF
recovery systems in operation at the airports in
Europe: Lulea, Sweden; Oslo, Norway; and
Munich, Germany.
Currently three vendors are actively designing,
testing or marketing ADF recovery systems for
on-site use at airports in North America: Deicing
Systems (DIS), Glycol Specialists, Inc. (GSI), and
Canadian Chemical Reclaiming (CCR). In addition,
there are a number of chemical waste service
companies that will provide off-site processing for
spent glycol for other industries. The technology
and process applications of ADF are evolving
rapidly. The equipment manufacturers and the
airport operators should be contacted for current
state-of-the-art information.
ADVANTAGES AND DISADVANTAGES
In order for the ADF to be recovered or
regenerated, it must first be collected at the airport.
The implementation of ADF collection must be
coordinated to meet the unique requirements of
each airport. The feasibility of glycol recovery is
dependent on the ability of the collection system to
recover a relatively concentrated waste stream
without significant contamination by other storm
water components. Since distillation is an energy-
intensive process, it is generally not cost effective to
distill and recycle waste glycol solutions at low
concentrations (< 15 percent). However, individual
airports may have to collect and recover lower
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concentrations of waste glycol solutions to satisfy
requirements of their storm water NPDES permits.
One method for collecting a more concentrated used
glycol stream is to conduct deicing at a remote or
centralized location. However, centralized deicing
systems may be impractical for all but the largest
airport operations due to their cost and physical
size. For established airports, a switch to
centralized deicing systems would present a number
of operational and logistical problems. In lieu of a
centralized facility, used glycol can be collected via
vacuum trucks and fluid collection containers that
siphon glycol from runway aprons. Roller sponge
devices have been employed at the Toronto Airport
with mixed results due to the irregularity of runway
surfaces.
Mixtures of ethylene and propylene glycol s cannot
be recovered effectively in a single batch process
because the technology currently available does not
cost effectively separate the two glycols. While
there is a market for either recovered ethylene
glycol or propylene glycol, there is little demand for
a recovered blend of both glycols by end users. In
order to recover either ethylene glycol or propylene
glycol from spent ADF, an airport must use one or
the other, or isolate application and runoff areas.
Treated separately, each type of water-glycol
mixture can then be recovered effectively via the
distillation process.
While the potential for volatile-organic emissions
from the recovery process to the air is considered
small, the air emissions from the distillation process
through losses from condenser vents, accumulator
tank vents, and storage tank vents must be
considered. Ion-exchange flush and spent
wastewater that are generated by recovery
processes may generally be discharged to a sanitary
sewer. These spent byproducts may require
neutralization through the addition of acids or bases
before discharge. Discharges to the sanitary sewer
system may require permitting under local
pretreatment programs. Spent filter cartridges may
be generated in some systems, although in most
cases these can be disposed in the local landfill.
After a distillation condensate with a glycol
concentration of 7-10 percent is generated, it is
commonly reused or disposed depending on the
nature of the runoff and the economics involved.
Recently the EPA officially changed the reportable
quantity for ethylene glycol from 1 pound to 5000
pounds. If more than 5000 pounds of the glycol, as
concentrate, is released into the environment, then
the release needs to be reported under the
Comprehensive Environmental Response,
Compensation and Liability Act (CERCLA) and
Emergency Planning and Community Right to
Know Act (EPCRA). A spill prevention control and
countermeasure (SPCC) plan should also be
developed for all ADF systems to address the
handling, storage and accidental release of
chemicals, regenerated products and waste
byproducts.
DESIGN CRITERIA
There are a number of important criteria that must
be determined in order to properly design an ADF
system. Table 1 lists some of the key criteria. The
storage and handling of process chemicals, energy
requirements, and the disposal of spent chemicals
and residuals generated in the recovery process
must also be carefully considered. Other factors,
such as site drainage, weather patterns, water
quality requirements, state and local restrictions,
marketability of the recovered product, etc., will
also influence the final design of the system.
Sodium hydroxide (NaOH) and hydrochloric acid
(HC1) are required for regeneration of the ion
exchange process unit. As a part of the
recertification process, wetting agents and a
corrosion inhibitor must be added to the recovered
product prior to its reuse as airplane deicing fluid.
While recertification and reuse of recovered
airplane deicing fluids is practiced in Europe, the
FAA currently has no recertification guideline for
reuse of recovered ADF in the United States.
For the most part, energy requirements for the
recovery process are dependent on the waste stream
glycol concentration of the fluid to be recycled and
the purity required by the end user. Recovery by
distillation is energy-intensive, with nominal energy
requirements being about 250 to 1200 BTUs per
pound of feed. As the technology is refined and as
operating experience grows, these costs should
decrease. Flush and spent wastewater are generated
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TABLE 1 KEY CRITERIA FOR
DESIGNING AN AIRPLANE DEICING
FLUID RECOVERY SYSTEM
Deicing Fluid Data
-Type
-Concentration
-Total Consumption per Season
-Total Consumption per Peak-day
-Average Consumption per Aircraft
Airport Operations Data
-Flights per Day
-Peak Traffic Periods
Length of Deicing Season
-Number of Deicing Days per Season
-Future Traffic Extension Plans
Spent Fluid Data
-Volume Generated
-Glycol Concentration
Reuse Specifications
-Glycol Concentration
-Acceptable Impurities
Source: Kaldeway and Legaretta, 1993.
by recovery processes which employ ion-exchange
systems. After neutralization through the addition
of acids or bases to the sanitary sewer, the fluids can
be disposed. Spent filter cartridges may be
generated in some systems and may be sent to a
landfill for disposal. Distillation condensate, with
less than 1.5 percent glycol according to local
landfill operator requirements, is also generated and
may be reused or disposed. Currently discharges to
the sanitary sewer system may require permitting
under local pretreatment programs.
PERFORMANCE
Three ADF recovery systems were evaluated using
data provided by three vendors. In each ADF
recovery system investigated, the quality of the fluid
recovered was dictated by the specification
obj ective. The data provided for the ethylene glycol
recovery system at the Toronto Airport shows that
the process reliably produced an effluent with a
glycol content over 80 percent. The data from the
ADF recovery system in Denver also showed that
high purity (98.5 percent glycol) can be reliably
produced. The process at the Munich Airport
reliably produced an effluent with a glycol content
over 50 percent, which meets the lower end-user
requirements in Europe.
COSTS
Since there are no full-scale ADF systems currently
operating in the U.S., it is difficult to determine the
actual construction costs for these systems.
However, based on the pilot study at the Denver
Stapleton Airport, the total capital cost for the
complete project, including deicing and anti-icing
application equipment, collection piping, storage
facilities, and a glycol recovery system, has been
estimated to be between $6 and $7 million dollars.
The construction costs for the ADF collection
system, storage and handling facilities, piping, and
recovery system has been estimated at
approximately $600,000 (GSI, 1993).
The total capital cost for the new system at the
Denver International Airport, including deicing and
anti-icing application pads and equipment, drainage
and collection piping, storage and handling facilities,
and complete glycol recovery system is currently
estimated at between $20 and $25 million dollars.
These costs are based on a complete package, and
include planning, engineering design, equipment,
construction and installation, start-up services, and
other contingencies. The construction costs for the
ADF collection system, storage and handling
facilities, piping, controls and instrumentation, and
a complete recovery system, is currently estimated
at approximately $5 million dollars.
The major operating expense for all ADF systems is
the cost of energy used in the distillation process.
Maintenance costs include flushing of filters and
ion-exchange units, disposal of spent filter
cartridges, purchasing process and neutralization
chemicals, lubricating pumping equipment, and
inspecting and repairing distillation equipment and
heat exchangers. The collection system and storage
facilities will also require periodic cleaning and
maintenance. Based on very limited operating data
from the pilot study at the Stapleton Airport, the
cost for processing ADF with a 28 percent glycol
concentration is approximately 35 cents per gallon
treated. However, this cost will vary depending on
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the volume treated and the concentration of glycol
in the waste stream. As the technology is refined
and as operating experience grows, these costs
should decrease.
REFERENCES
9. Hartwell, S.I., D.M. Jordahl, and E.B. May,
1993. Toxicity of Aircraft Deicer and
Anti-icer Solutions to Aquatic Organisms.
Chesapeake Bay Research and Monitoring
Division, Annapolis, Maryland. Document
Number CBRM-TX-93-1.
American Association of Airport 10.
Executives, 1993. Conference on Aircraft
Deicing. Washington, D.C.
Comstock, C., 1990, as cited in R.D. Sills
and P. A. Blakeslee, 1992. "The 11.
Environmental Impact of Deicers in Airport
Storm Water Runoff," in Chemical Deicers
in the Environment, ed. Frank M. D'ltri.
Lewis Publishers, Inc., Chelsea, MI.
ENSR Consulting and Engineering, 1993. 12.
Evaluation of the Biotic Communities and
Chemistry of the Water and Sediments in
Sand Creek near Staple ton International
Airport. Prepared for Stapleton
International Airport. Document Number
6321-002. 13.
Freeman, H.M, 1989. Standard Handbook
of Hazardous Waste Treatment and
Disposal. McGraw-Hill, New York, N. Y.
Federal Aviation Administration, Advisory 14.
Circular (150/5320-15), 1991.
Management of Airport Industrial Waste.
U.S. Department of Transportation,
Washington, D.C.
Federal Register Notice, November 16,
1990. EPA Administered Permit Programs; 15.
the National Pollutant Discharge
Elimination System, Vol. 55, No. 222, page
48062.
Federal Register Notice, November 19,
1993. Fact Sheet for the Multi-Sector Storm
Water General Permit (Proposed), Vol. 58, 16.
No. 222, page 491587.
Federal Register Notice, June 12, 1995. 17.
Reportable Quantity Adjustments, Vol. 60,
No. 112, page 30925.
Health Advisory, 1987. Ethylene Glycol.
Office of Drinking Water, U.S.
Environmental Protection Agency.
Document Number PB87-235578.
Kaldeway, J., Director of Airport
Operations. L.B. Pearson International
Airport, Toronto, Canada. 1993. Personal
communication with Lauren Fillmore,
Parsons Engineering Science, Inc.
Legarreta, G., Civil Engineer. Design and
Operations Criteria Division, Federal
Aviation Administration. 1993. Personal
communication with Lauren Fillmore,
Parsons Engineering Science, Inc.
Lubbers L., 1993. Laboratory and Field
Studies of the Toxicity of Aircraft Deicing
Fluids. Presentation to the SAE Aircraft
Ground Deicing Conference, Salt Lake City,
Utah, June 15-17, 1993.
McGreevey, T., 1990, as cited in R.D. Sills
and P.A. Blakeslee, 1992. "The
Environmental Impact of Deicers in Airport
Storm Water Runoff," in Chemical Deicers
in the Environment, ed. Frank M. DTtri.
Lewis Publishers, Inc., Chelsea, MI.
Morse, C., 1990, as cited in R.D. Sills and
P.A. Blakeslee, 1992. "The Environmental
Impact of Deicers in Airport Storm Water
Runoff," in Chemical Deicers in the
Environment, ed. Frank M. DTtri. Lewis
Publishers, Inc., Chelsea, MI.
NIOSHTIC™ Search Results - Ethylene
Glycol, Propylene Glycol.
Roberts, D., 1990, as cited in R.D. Sills and
P.A. Blakeslee, 1992. "The Environmental
Impact of Deicers in Airport Storm Water
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Runoff, in Chemical Deicers in the
Environment, ed. Frank M. D'ltri.
Lewis Publishers, Inc., Chelsea, MI.
18. SAE International, May 17, 1993.
Unconfirmed Minutes of Meeting No. 37 of
AMS Committee, Rome, Italy.
19. Sills, R.D. and P.A. Blakeslee, 1992. "The
Environmental Impact of Deicers in Airport
Storm Water Runoff," in Chemical Deicers
in the Environment, ed. Frank M. D'ltri.
Lewis Publishers, Inc., Chelsea, MI.
20. Transport Canada, 1985. State-of-the-Art
Report of Aircraft Deicing/'Anti-icing.
Professional and Technical Services,
Airports and Construction, AirportFacilities
Branch, Facilities and Environment
Management. Document Number
AK-75-09-129. (Type I Fluid Only).
21. Verschueren, K., 1983. Handbook of
Environmental Data on Organic Chemicals.
2nd Edition, Van Nostrand Reinhold Co.,
New York, N. Y.
ADDITIONAL INFORMATION
Energy and Environmental Research Center
John Rindt
1219 83rd Street South
Grand Forks, ND 58201
Federal Aviation Administration
George Legarreta
Office of Airport Safety and Standards
800 Independence Avenue, SW
Washington, DC 20591
Metropolitan Airports Commission
Richard Keinz
6040 28th Avenue South
Minneapolis, MN 55450
The mention of trade names or commercial products
does not constitute endorsement or recommendation
for the use by the U.S. Environmental Protection
Agency.
AAA Environmental Services Cooperation
Thomas Cannon
1800 Second Street, Suite 808-13
Sarasota, FL 34236
Denver International Airport
Bob Nixon, Senior Engineer
8500 Pena Boulevard
Denver, CO 80249
ECOLO Corp Inc.
Lee Howar
1515 Jefferson Highway, Suite 817
Arlington, VA 22202
For more information contact:
Municipal Technology Branch
U.S. EPA
Mail Code 4204
401 M St., S.W.
Washington, D.C., 20460
MTB
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Exceience fh compliance through optftnal technical safaris:
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