Soil Biodegradation of Propylene Glycol Based Aircraft Deicing Fluids

Abstract

The discharge of untreated aircraft deicing fluid (ADF) wastes to surface water and stormwater collection systems is largely prohibited in the U.S., and many airports are searching for alternative methods for managing ADF wastes. A series of soil pan studies were conducted to examine soil biodegradation as a treatment for managing ADF wastes on site. The soil pan studies were designed to evaluate system operating conditions and surface application rates required to enhance biotreatment kinetics and propylene glycol removal. Results indicate that biodegradation of propylene glycol in soil followed first‐order kinetics. Soil aeration, lime amendment, and sludge amendment increased the “base level” first‐order loss coefficient by as much as a factor of 4. Degradation of propylene glycol to practical quantitation levels (10 to 17 mg/kg soil; dry weight basis) was observed in soils receiving ADF solutions of 5, 10, and 20% by weight at corresponding initial propylene glycol concentrations of 7016, 14 032, and 28 064 mg/kg. Biodegradation was severely inhibited when a 40% by weight ADF solution was applied to the soil. A reduced lag phase and increased rate of propylene glycol degradation occurred when ADF solutions in the range of 5 to 10% by weight were reapplied to soils.