Expanding the facility will allow the plant to process wastewater of 450,000 people, up from the 210,000 people currently. Luxembourg City counts around 120,000 inhabitants but the plant also receives wastewater from Bertrange and Strassen, Leudelange-Schléiwenhaff, Roedgen and Findel.

Construction is expected to begin in 2023 and works should take until 2030 to be completed. The city is looking for financial support from the state to the tune of €106m, according to the Luxemburger Wort.

Between 2017 and 2021, the Beggen wastewater treatment plant was already modernised at a cost of €52m. This came after the European Court of Justice had fined Luxembourg a lump sum of €2m in 2013 for violating EU wastewater regulation and another €2,800  per day until full compliance.

The court imposed the fine after finding Luxembourg non-compliant with the urban wastewater directive in 2006 and the grand duchy failed to bring all its plants up to speed within the following six years.

The plant in Beggen in 2020 processed more than 16m cubic litres of wastewater. 

Around 20m litres of wastewater leaked from the plant in a 2019 incident. A software error had caused a valve to open. The malfunctioning was only noticed 20 hours later as dead fishes were spotted in the Alzette. 

Luxembourg’s water management authority at the time said the plant urgently needed upgrading as it had reached its limits.