Deicing fluids based on Propylene Glycol are used at Stockholm Arlanda airport to remove or prevent ice on aircrafts. The high oxygen demand of propylene Glycol can cause oxygen depletion in rivers downstream from the airport if not collected. Mass balance calculations made by Swedavia indicate that the actual amount of gathered propylene Glycol is underestimated. Suspicions that propylene Glycol is degraded in the stormwatersystem designed to collect deicingfluids, called the B-Glycolsystem, have to be investigated in order to establish with certainty that no propylene Glycol in other ways leaves the B-Glycol system.The purpose of this study was to determine if degradation of propylene Glycol is present in the B-Glycol system and also to estimate the extent of the degradation. Propylene Glycols high biological oxygen demand can cause oxygen depletion in waters downstream from Stockholm Arlanda airport if not collected.

The aim of this thesis was to answer a number of questions about the environmental consequences of aircraft de-icing. A further aim was to suggest how the environmental consequences due to the release of de-icing fluids can be measured and reduced.The main impact of the aircraft de-icing on the environment is due to the large oxygen demand for the degradation of Glycol based de-icing fluids which are released in the environment. The effect of the increase in oxygen demand depends on where the degradation occurs in the ecosystem. In a sensitive ecosystem, the large demand of oxygen could provide an anaerobic environment which would be harmful for many types of organisms.In order to reduce the negative effects of the applied de-icing fluid, there is some type of collection system at every regular airport in Sweden. The methods of collection can be divided into two general groups, hydrological isolation or vacuum sweeper trucks.

Glycerol is essential for the lipid metabolism of both plants and animals. Glycerol is formed in the rumen by hydrolysis of lipids from the feed. Glycerol is also a by-product from the production of biodiesel from rapeseed oil and other fat sources. Glycerol might be used as a dietary glucose precursor for dairy cows in similar ways as propylene Glycol. Due to increased production of biodiesel more glycerol has been available to a lower price.