Aircraft deicing fluid

[1][2] Environmental concerns include increased salinity of groundwater where de-icing fluids are discharged into soil, and toxicity to humans and other mammals.

Other ingredients vary depending on the manufacturer, but the exact composition of a particular brand of fluid is generally held as confidential proprietary information.

The amount de-icing service companies charge end users is generally in the range of US$8 to US$12 per diluted gallon (US$2.10 to US$3.20 per liter).

De-icing fluid performance is primarily measured by Holdover Time (HOT), and Lowest Operational Use Temperature (LOUT).

In the United States, the FAA publishes official holdover time and lowest operational use temperature tables for all approved de-icing fluids, and revises them annually.

[9] For type I fluids, the Holdover Time listed in the FAA tables ranges from 1–22 minutes, depending on the above-mentioned situational factors.

Dilution, where necessary, must be done according to ambient weather condition and the manufacturer's instructions in order to minimize costs while maintaining safety.

Thickened fluids (types II, III, and IV) are intended to remain on surfaces after application in order to provide anti-icing protection.

[11] The objective of these standards is to ensure acceptable aerodynamic characteristics of the deicing/anti-icing fluids as they flow off aircraft lifting and control surfaces during the takeoff ground acceleration and climb.

Large quantities of dissolved oxygen (DO) in the water column are consumed when microbial populations decompose propylene glycol.

Hence, it is only partly removed in wastewater treatment plants and a substantial fraction reaches surface water such as rivers and lakes.