ARA Worblental

Aerial view of the plant

The Worblental WWTP is the third largest wastewater treatment plant in the canton of Bern and among the 15 largest WWTP in Switzerland. The facility is located in Worblaufen in the Bernese agglomeration community of Ittigen and is located on the Aare .

history

Primary clarifier

The community association ARA Worblental was founded in 1960. In 1971 the wastewater treatment plant was put into operation. In 2002, 2010 and 2011 the sludge treatment , the sludge removal system in the primary clarifier and the activated sludge plant were renewed. In between, in 2007, the fixed bed biology was put into operation, making the plant one of the most modern and efficient wastewater treatment plants in Switzerland. The company's own sludge dewatering was put into operation in 2016. In 2018, regionally relevant sewers and special structures were taken over by the local communities.

Catchment area

The catchment area of the ARA includes the communities Arni , Biglen , Grosshöchstetten , Worb , Vechigen , Stettlen , Bolligen and Ittigen in Worblental as well as Ostermundigen and Zollikofen . The community of Münsingen is also involved as a contractual partner .

ARA Worblental catchment area and sewer system

It covers an area of around 99 km² with around 70,000 inhabitants, a 39 km long canal system, eight rain overflow basins and other special structures.

technology

Activated sludge plant

Around 33,000 cubic meters of wastewater is cleaned every day in the Worblental ARA . This goes through three cleaning stages:

Mechanical pre-: Due to the coarse screen , the sand trap , the fine screen , the overflow basins as well as the primary clarifiers are solids such as from paper, faeces and sand.
Biological purification stage: In the activated sludge system , the secondary clarifier and the fixed bed system , impurities dissolved in the water are broken down by microorganisms .
Chemical cleaning stage: In the precipitant station , phosphates dissolved in the water are removed from the wastewater by adding a precipitant .

Flow diagram of wastewater treatment

In order to eliminate trace substances , around one hundred WWTPs in Switzerland must be equipped with an additional purification stage by 2040 at the latest. It is planned that the WWTP Worblental will be expanded by 2035.

The treated wastewater is discharged into the middle of the Aare.