Department Process Engineering

Wastewater in alpine areas

Decentralised treatment and reuse of toilet wastewater in alpine areas

In the last century, the upper alpine region experienced a major change in activities, from a pure agricultural land use toward an increased use for tourism. The Swiss Alpine Club (SAC) alone operates 153 Alpine huts for about 300`000 overnight stays each year and about 1`000`000 day visitors. In addition, hundred thousands of winter sports tourists enjoy daily the high mountain Environment. 

Because of the special location of these infrastructures (see picture above) the problematic of water supply and wastewater disposal is particularly significant. In many cases no supply with melt or spring water exists. Furthermore it turns out to be especially difficult and complex to dispose the produced wastewater in a conventional way. Due to its high contamination level wastewater cannot be disposed off as such, posing a threat to environment and spring water quality especially in karstic regions. The option of piping it down to a valley wastewater treatment plant (WWTP) however generates high construction and maintenance costs.

In this project the operation of Europe's highest biological WWTP in the ski resort of Zermatt is investigated. The plant, based on Membrane Bioreactor (MBR) is located in a cable car mountain station, 10'781 ft. above sea level (see plant scheme). The negative impact on sensitive mountain environment is minimized by using the treated wastewater again as flush water for the toilets. The project deals with treatment, disposal and long term maintenance questions. In a global view the project is of great importance, it covers problems existing hundredfold in the Alps and furthermore re-use of treated wastewater (only urine) will definitely be of great importance for arid regions all over the world. The operation of the plant is a joint venture of Zermatt Bergbahnen, terraLink Gmbh and of Eawag. The project is financially supported by the Swiss Federal Office for the Environment (BAFU).

The Jury of the Mülheim Water Award, which was given for the first time in 2006, was positively convinced by the project results (more). The award is supported by the IWA (International Water Association).

Detailed informations about the project are given in the paper.