Date of Award


Document Type


Degree Name

Master of Science


Department of Systems Engineering and Management

First Advisor

Charles A. Bleckmann, PhD


Aircraft de-icing fluids (ADFs) are used worldwide to ensure safe aircraft operations. This research effort was conducted to analyze the biodegradation effects of two chemical components of ADFs, propylene glycol (PG) and tolyltriazole (TTA), in a high-clay soil. The research used four test methods; automated respirometry, high performance liquid chromatography (HPLC), microbial colony population counts (MCPC), and agar well diffusion tests (AWDT). The research was partitioned into two phases of investigation. Phase-one analyzed individual and combined ADF chemical components on uncontaminated soil. The presence of TTA, from 25 - 1,000 mg/kg, reduced the maximum respiration rate of 1,000 mg/kg PG alone; however, cumulative respiration over the two-week study period was proportionality higher for TTA (25 - 500 mg/kg). Rate and respiration totals for soil exposed to TTA (25 - 750 mg/kg) alone, were not significantly different from background soil; however, rate and respiration totals for PG (1,000 mg/kg) alone were significantly higher. The HPLC percentage of recovered TTA, with or without PG presence, indicated a loss (biodegradation and/or absorption) of TTA within the soil. Kellner (1999) conducted HPLC for absorption/desorption of TTA on the same (high-clay) soil. MCPC and AWDT indicated no measurable toxic effects to microbial populations/health occurred from ADF chemical components. Phase-two research conducted reapplication of ADF chemicals on acclimated soils from phase-one. Initial respiration rates from application of 1,000 mg/kg PG on acclimated soil (PG 1,000 mg/kg) compared to 1,000 mg/kg PG on uncontaminated soil. The acclimated soil produced a significantly larger initial rate of respiration.

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