Wastewater too becomes a resource

He is responsible for the drinking water and wastewater division: Martin Atzwanger, Managing Director, talks here about the challenges and special features of this branch of ATZWANGER's business.

When did the commercial sector for drinking water and wastewater treatment plants come into being?

“We were already experts in the field of pool water treatment. The filtration process for drinking water is basically similar, so it was an obvious area to move into. Wastewater is a different matter: this topic became interesting for us at ATZWANGER when the first centralised wastewater treatment plants were built in South Tyrol in the 1980s. As experienced plant engineers, we quickly built up the necessary expertise in this area. As the Province of Bolzano had commissioned the Collegio Costruttori della Provincia Autonoma di Bolzano (Association of Builders of the Autonomous Province of Bolzano) to construct several wastewater treatment plants, including those in the city of Bolzano, ARA Tobl in San Lorenzo di Sebato and San Candido, ATZWANGER was entrusted with the technical side of the project. This eventually led to the creation of a separate department within the company, and ultimately an entire division.”

What are the strengths?

“We have always strived to develop and offer the best technological solutions. Through technology scouting and constantly searching for the latest developments, we are able to implement even the most complex systems – customised to meet specific requirements. We also have our own department that handles public tenders and the necessary certifications and registrations.”

What role does the drinking water treatment play?

“There is relatively little demand for this, because here in South Tyrol, the drinking water is actually very good. We have developed specific applications for special requirements, such as eliminating contamination with arsenic, iron or manganese, or reducing the acidity in drinking water.”

The situation is different for wastewater treatment plants …

"In South Tyrol, we at ATZWANGER have now completely rebuilt all wastewater treatment plants from scratch or expanded and renovated them over the years. There are only five operators nationwide, and thanks to our consistent performance, we have built up a genuine relationship of trust with them. We have also carried out important projects for major Italian plant operators such as SMAT in Turin, IREN in Parma, Acquedotto Pugliese in Bari and others outside Italy. In Lithuania, for example, we completely renovated the largest wastewater treatment plant in the capital Vilnius for the municipal utility company Vilnius Vandenys, which has a treatment capacity of 900,000 PE (population equivalent). In Croatia, our ATZWANGER team was able to design and implement an innovative, modular wasterwater treatment plant for the Adriatic city of Rovinji.”

Is wastewater treatment all about purifying water?

“That is, of course, the main task, and we use membrane technology for this purpose in suitable situations. It is the most modern way of purifying water and making it usable again for various applications. However, wastewater treatment plants can also function as energy producers. Examples of this are the Branzoll/Branzolo wastewater treatment plants and the recently completed expansion of the plant in Sinich/Sinigo Meran/Merano, where industrial wastewater with a high organic content is fed into reactors for anaerobic high-load fermentation. There, the organic material is converted into biogas through a biological process. This in turn generates heat and electricity. These plants even operate independently and feed surplus electricity into the grid. In addition, sewage sludge is also produced, an issue to which we at ATZWANGER pay particular attention”.

How is sewage sludge managed?

“Until now, sewage sludge has been dewatered, possibly dried, and either composted or spread on agricultural land. However, it has now been recognised that sewage sludge also accumulates increasing amounts of contaminants such as microplastics, hormones, etc., which can enter the food cycle when spread on land.

The only sensible disposal option for sewage sludge in the near future will therefore be mono-incineration. This reduces the volume, eliminates harmful substances and, from the residual ash, rich in phosphorus, it is possible to obtain this important fertiliser for agricultural use. In the near future, such disposal facilities are to be built in Europe, Italy and probably also in South Tyrol.”