Date of Award

Summer 1999

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)


Civil, Construction, and Environmental Engineering

First Advisor

Zitomer, Daniel H.

Second Advisor

Zanoni, A. E.

Third Advisor

Crandall, Clifford J.


The airline industry has found itself in a difficult position in the last decade. The increased need for de-icing/anti-icing activities increased the use of aircraft de-icing/anti-icing fluid (ADF), which in turn increased the amount of ADF which drained into many airports' stormwater systems. These practices make it difficult to meet regulations regarding non-point source pollution, which include runoff from airports. Research results have shown that anaerobic treatment of aircraft de-icing/anti-icing runoff is a viable option, but the lack of nutrients in the runoff makes nutrient amendment necessary. Research regarding co-digestion of aircraft de-icing/anti-icing runoff and municipal sludge by anaerobic treatment has shown that the addition of municipal sludge lends nutrients to the process, but the high concentration of ADF COD is still difficult to treat under some conditions. The research reported herein compared conventional and phased co-digestion configurations. It was determined that phased systems typically out-perform comparable conventional systems in terms of methane production and maximum sustainable organic loading rate. The municipal sludge lends nutrients and alkalinity to anaerobic systems which aircraft de-icing/anti-icing runoff (ADR) lacks. The treatability of ADR by unacclimated anaerobic sludge was compared to acclimated sludge, and it was determined that acclimation leads to somewhat higher propylene glycol methanogenesis rates, but the relatively small increase may be insignificant under some conditions. During analysis of volatile fatty acids and other intermediates, propionaldehyde was identified as a more significant intermediate of propylene glycol ADR biotransformation than propionate under some conditions. This finding is significant because propionaldehyde fermentation to acetate at high hydrogen partial pressures is more energetically feasible than propionate fermentation to acetate, potentially making methane production faster and more complete. Also, propionaldehyde is more toxic than propylene glycol ethylene glycol and their other methanogenic intermediates, a concern in the environment. This is the first published report of propionaldehyde as a significant intermediate in the anaerobic conversion of propylene glycol to the author's knowledge. It is recommended that future research should be conducted regarding propionaldehyde as an intermediate in the biodegradation of propylene glycol during phased methanogenesis.



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