Water and water protection

Flughafen Zürich AG is naturally committed to the careful use of fresh water and to the appropriate cleaning of waste water.

Fresh water

Drinking water for Zurich Airport comes from the municipal water supply for the town of Kloten. In addition, groundwater is used as process water. Groundwater is already pumped away in order to keep dry some older buildings in the main airport complex that cannot be adequately sealed. Rainwater is also used to flush some toilets, including in the Circle now as well.

GENERAL DRAINAGE PLAN

Like the communities in the Canton of Zurich, Zurich Airport has its own general drainage plan (GEP). In line with the “avoid – separate – treat” approach, the aim is to produce as little waste water as possible. Along with measures to ensure drainage systems comply with the law, the drainage plan includes stipulations relating to the operation and maintenance of the existing sewage and pump systems.

Dirty water runs out of the discharge channel into the retention filter basin.

Domestic and industrial waste water

Various types of waste water are produced at the airport which are each treated in different ways. All domestic waste water, from toilets or restaurant kitchens for example, is channelled into the local sewage treatment plant at Kloten-Opfikon where it is treated. The sewage plant, which is a joint venture between Flughafen Zürich AG and the municipalities of Kloten and Opfikon, is currently being upgraded and extended (while operations continue uninterrupted). The contents of grease separators are sent to a biogas plant. Special waste water, from workshops or from aircraft toilets for example, requires pre-treatment before it can likewise be sent to the sewage plant.

Aircraft and runway de-icing

In order to ensure safe flight operations, in winter it is essential to keep both aircraft and operational areas free of ice. The winter of 2019/20 was the mildest one since records began with very little ice and snow, so far less de-icing agent was used. Consequently, there was also less contaminated runoff to be cleaned. 982 m³ of agents (propylene glycol) were used for aircraft de-icing (54% less than the previous year). 112 m³ of liquid de-icing agents (–92%) were required for runways, taxiways and aprons. 60 tonnes of conventional de-icing salts were additionally used on service roads, in the car parks and around the maintenance area.

Treatment of waste water from de-icing operations

De-icing aircraft with hot water and propylene glycol as well as spraying potassium formate-based de-icing agents on operating surfaces results in waste water contaminated with carbon compounds. If this waste water were to enter natural watercourses untreated, it would remove oxygen from the water and therefore cause problems for aquatic organisms. To prevent this, the waste water is collected and is then treated depending on the level of carbon concentration. Water that is only slightly polluted is first channelled through retention filter basins and then into the Glatt. Medium-contaminated waste water is sprayed over grassed areas using a special sprinkler system. As the water filters down through the soil, the glycol it contains biodegrades completely. Heavily contaminated waste water is treated in the airportʼs two distillation plants, where the glycol is concentrated and then supplied as a raw material to industrial companies.

Over the winter of 2019/20, 98% of the runoff was collected, slightly more than in the previous year. Of the 227 tonnes of carbon captured, 5 tonnes (2019: 30 tonnes) or just 2% flowed untreated into the Glatt.

Amount of de-icing runoff collected.