Well hidden inside the mountain on the edge of the village of Zermatt the wastewater treatment plant (ARA Zermatt) has been treating the waste water from the well-known health resort at the foot of the Matterhorn since 1982. Both the dirt loads as well as the requirements for effluent quality have increased ever since, making an expansion of biological treatment grades necessary. In 3 1/2 years of construction it was necessary to convert the original activated sludge plant to a membrane bioreactor plant. Its small space requirement and the excellent quality of the treated waste water are among the outstanding benefits of this system.
In several stages, the renewal of the ARA Zermatt was realized during the short construction season between Easter and Christmas. With sharp seasonal fluctuations in population numbers, the effluent quality had to be ensured at all times.

Seamless material flow in the narrow tunnel system

For rebuilding several GIS cranes were perfectly integrated into the mountain and stood for months, multi-layered to ensure a continuous and effortless flow of material under the most adverse climatic conditions in continuous use. The crane systems are 2 frequency-controlled underslung travelling cranes and a total of 9 monorails. The travelling cranes have a very low headroom to transport the bulky membrane cartridges in the narrow corridors. The power supply is made in the longitudinal direction via conductor lines and transversely thereto on C-rails with trailing cable. Even after completion of the innovative membrane bioreactor system a seamless material flow is guaranteed in the narrow tunnel system.

Hot zinc-plated crane defies aggressive atmosphere

Simultaneously with the reconstruction of the biological purification stages, a new building was constructed for the sludge treatment plant. Using centrifuges the sludge is deprived of water and in the air treatment plant all odour emissions are eliminated. The GIS travelling crane in a hot zinc-plated version defies even the prevailing aggressive atmosphere.

Author: Arthur Kemény, CH-5363 Weggis