Outokumpu Forta enabled innovative wastewater treatment tanks

Claudia Fischer


A wastewater treatment tank has to withstand high water pressure and the material needs to be corrosion-resistant as well as easily weldable.


The first wastewater treatment plant using Invest-Tech’s new tank design built of Outokumpu Forta LDX 2101 was recently set into operation.


Approximately 120 tons of Outokumpu Forta LDX 2101 duplex stainless steel.

Outokumpu Forta enabled innovative wastewater treatment tanks

Water is an increasingly scarce resource. And the worldwide rising consumption of fresh water makes wastewater treatment more and more important. Traditionally, wastewater treatment plants work with round tanks. The disadvantage of such round tanks is that their capacity cannot be expanded in case of increasing wastewater volumes. New tanks have to be built to expand capacity.

Invest-Tech, a Polish company specialized amongst others in planning and building wastewater treatment plants, has developed and patented a new, modular concept for wastewater tanks that makes them much more flexible for expansion. The Invest-Tech tanks are built out of separate stainless steel segments in square or rectangular shape so that they can be flexibly extended whenever necessary. Additional flexibility is given as the segments are bolted together and not welded. Tightness of the bolted elements is guaranteed by a polymer-polyurethane sealing system – a proprietary technical development of Invest-Tech as well.


High pressure requires excellent strength

“The special challenge that we are facing with this kind of tanks is the water pressure. A tank with dimensions 23 x 11 x 6 meters, containing 1,200 cubic meters water has to withstand a pressure of approximately 0.6 bar in a straight wall of 23 meters with a deflection of maximum 10 mm only,” explains Marcin Stanik, the responsible project manager at Invest-Tech. “For this reason, we had to choose a material that offers the necessary strength but also corrosion resistance and good weldability – as there are still elements that require welding. And for us there was no better choice than duplex stainless steel from Outokumpu.”

The first wastewater treatment plant using Invest-Tech’s new tank design built of around 120 tons of Outokumpu Forta LDX 2101 was recently set into operation with an official opening ceremony.

Now, Invest-Tech is planning to promote their design concept together with Outokumpu not only in Poland but also in other EU countries as perfect solution for smaller villages that might need to extend their wastewater treatment capacities in the future. “We are really looking forward to continue working with Outokumpu on this project,” says Sławomir Jezierski, Managing Director Invest-Tech. “We have already a long-standing successful partnership with Outokumpu in other business areas and know them as reliable partner who delivers high-quality material and services that meet our and our customers’ requirements.”

“This was an outstanding example of cooperation between Product Management, Technical Market Development and Sales on one side and high demanding but extremely reliable customer on the other side,” adds Elżbieta Kasprzycka from the Sales Department of Outokumpu‘s Coil Service Center Poland. “What is even more important – we see a big potential for our future cooperation and expanding market opportunities.”

Recommended products and insight

Building and infrastructure

Landmark buildings and bridges make a statement. When they’re built of stainless steel, that statement reflects an enduring legacy – a legacy of timeless beauty, exceptional strength and unmatched durability.

Structural applications

An inspired choice for load-bearing structures, stainless steel delivers exceptional strength with added benefits – like the corrosion resistance of steel in the Supra range, and light weight of high-strength duplex steel in the Forta range.


The Forta range contains duplex and other high strength stainless steels that enable thinner structures and weight reduction (measured in Rp0.2 > 400 MPa. PRE 16 to 43).


Outokumpu offers a full range of stainless-steel rebar with high availability. 

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