Denmark’s largest UV system is in operation

As much as 22 million litres of drinking water – or the equivalent of almost nine Olympic swimming pools – the new and modern UV system that HOFOR has installed at Tinghøj will be able to treat every hour. This makes the system the largest ever installed in Denmark, and it positions itself among the largest in the whole of Europe.

Silhorko-Eurowater is responsible for construction and installation of the new UV system, which replaces an older system with lower capacity and lower energy efficiency.

A large part of Copenhagen's water supply is stored in HOFOR's huge storage facility in the northern part of the city. Here, the water from several waterworks enters and flows through a large valve structure.

”The valve structure regulates the water inflow and thus the water pressure in the city, but also has an important function as an additional hygienic barrier that always gives consumers the security of having healthy and safe drinking water in the taps. And this is where ultraviolet light comes into the picture - to inactivate any unwanted microorganisms in the water,” says Erling V. Fischer, Project Manager at HOFOR, and continues:

”The replacement takes place because the city is growing and because we see a changed consumption pattern, which means that we need even greater capacity. The new UV system is therefore more than twice as large as the old one. At the same time, we take the opportunity to acquire a more modern, efficient, and sustainable technology that ensures less energy consumption, reduced need for service and maintenance as well as increased supply security.”

UV light ensures pure drinking water

Tinghøj's new UV solution comprises two UV disinfection systems, each of which can treat as much as 11 million litres of water per hour. This ensures ample capacity to cover consumption during peak hours in Copenhagen, even in case of repairs at one of the two systems.

The system's ultraviolet light (UV) disinfects the water, thereby providing extra assurance that the drinking water sent out to consumers is of the best quality possible. UV light inactivates bacteria, viruses, and the like by breaking down the micro-organisms' DNA within a few seconds. Disinfection with UV light occurs without affecting the taste and quality of the water.

It was important to maintain the water supply to Copenhagen throughout the operation. Therefore, Tinghøj's old UV system was replaced by the new solution in two stages, so that one system was kept in operation while the other was replaced.

The two new UV systems were welded to stainless foundations in advance, so that the assembly work on site was made as straightforward as possible. In practice, this meant that although the installation required cooperation between many different professional groups, it was successfully completed in just 18 hours and without any water interruptions.

”Each system weighs more than three tonnes and has a total of 132 lamp cables with an overall length of over 2.5 km, so it was a heavy and complicated job to get them into place and get both pipes, valves, wiring and control to form a synthesis. But everyone played their role perfectly, and the installation thus became a class example of how with good cooperation you can reach the goal surprisingly quickly,” says Thorbjørn Skanse Hinge, UV Product Specialist and Project Manager at Silhorko-Eurowater.

The following representatives were gathered for the inauguration of the new UV systems at Tinghøj (from left to right): Thorbjørn Skanse Hinge (SILHORKO-EUROWATER), Peer Krueger (Wedeco), Erling V. Fischer (HOFOR), Thomas Franz (Wedeco), Tim Rindsig (Xylem Water Solutions Denmark), Torben Buhl (SILHORKO-EUROWATER), David Fogde (HOFOR), Thomas Drifte (HOFOR) and Michael Petersen (HOFOR).

Part of a large order

In the spring of 2020, SILHORKO-EUROWATER and HOFOR signed the largest UV deal in Danish history: Delivery of a total of 35 UV systems with installation, commissioning, spare parts, service, and support.

The systems are delivered over several years, alongside new construction or modernization of the waterworks in and around Copenhagen to achieve an even higher long-term supply security. Last year, the waterworks at Marbjerg, just outside Roskilde, installed a new UV system as the first in the delivery. At present, 12 out of the 35 systems have been delivered.