Well-planned expansion of the Meran/Merano wastewater treatment plant

The expansion of the wastewater treatment plant was completed and handed over to Eco Center AG/S.p.A. in December 2025. ATZWANGER led the temporary consortium (with Unionbau AG/SpA, Elettro S.E.A. GmbH/Srl and Erdbau GmbH/Srl) that was awarded the project contract.

The expansion project, worth approximately €17 million, consists of the construction of a separate industrial wastewater treatment plant at the entrance to the Sinich/Sinigo (Meran/Merano) treatment plant and the expansion of the cogeneration plant. The Merano wastewater treatment plant was designed for a capacity of 364,000 population equivalents. ‘However, treating industrial wastewater separately reduces the load on the Meran/Merano WWTP by the equivalent of 300.000 inhabitants,’ explains Eng. Roberto Cossetto, responsible project manager and head of the wastewater/drinking water department at ATZWANGER. This process generates a significant amount of energy, more than the plant needs, produces less sewage sludge and reduces costs for the community. ‘Thanks to our state-of-the-art technology, industrial wastewater becomes a resource,’ emphasises the expert.

The wastewater treatment plant as an energy generator

Currently, industrial wastewater from Forst and Zipperle flows through a dedicated sewer system into the new 6.000 m³ collection basin. The process then moves on to a pre-treatment plant comprising two reactors with a filter system for anaerobic high-load fermentation. There, the organic matter in the heated (34 °C) wastewater is converted into biogas through a biological process. This generates heat and electricity, with a maximum electrical output of 1,800 kW. This is around 800 kW more than the plant itself requires, enabling it to operate self-sufficiently and feed electricity into the grid.

“It was a race against time for everyone,” recalls Cossetto. “Due to partial financing under the PNRR (National Recovery and Resilience Plan) , it had to be completed by 2025. That's why we held 90 face-to-face construction meetings in just under two years. It was an intense period, but we are proud to have achieved our ambitious goals with the help of our dedicated team!”