Jernhusen, Region City

During a geotechnical field study for a city development project at Gothenburg Central Station, property manager Jernhusen needed a water treatment solution that were able to clean drilling water. Swedish Hydro Solutions was the only company to deliver. With the help of chitosan treatment, the project requirements were achieved.

The drill water became crystal clear

The company

The state-owned management company Jernhusen, formerly part of SJ, owns, develops and manages properties along the railroad. The properties include railway stations, office buildings, terminals and train stations. Their goal is, among other things, to make the train journey attractive for the passengers. As part of this, they develop the areas adjacent to the railway stations, the development plans includes building new offices, housing and commercial properties.

The challenge

Jernhusen plans to create a new district, Region City, north of Gothenburg Central Station. In front of the building, the company needed to commence a geotechnical field survey to check the nature of the soil and ground. As test drilling will occur during the geotechnical survey, they needed a treatment method that were able to handle the drilling water, which is often dirtier and harder to clean than ordinary process water.

Most market participants offer only expensive solutions, including transportation by car to landfills as a method for handling the drilling water, which is a huge waste of water, says Åsa Wetterberg, construction project manager at Jernhusen.

The company set out to find a working purification method which could achieve the high purification standards set by Göteborgs Stad.

The solution

Swedish Hydro Solutions preliminary investigation indicated that the water contained a lot of drilling mud and particles along with high levels of particulate metals, but no dissolved contaminants. To clean the water, mobile passive chitosan flocking was used in two sedimentation tanks. In addition, the pH was adjusted with carbon dioxide.

Åsa Wetterberg thinks that the solution is easy to use.

– Swedish Hydro Solutions trained one of the crew members at the workplace to manage the treatment plant, which was easy to do. All he had to do was to wash the Biosocks every two hours and check the pH level in the outgoing water.

The result

Every day during the project about 10 to 20 cubic meters of water was processed, and during the entire project it totaled to about 250 cubic meters.

Swedish Hydro Solutions was the only company that managed to clean the drilling water. It was very nice to find a treatment solution that gives great results while nevertheless being easy to use.

– They managed to get rid of all the particles and mud from the drilling water, so it became crystal clear. We succeeded in following Gothenburg’s high demands – the water also became significantly cleaner than the guideline value, says Åsa Wetterberg.

With Swedish Hydro Solutions’ technology, the cost was reduced compared with running water to landfill – a saving of 130,000 SEK. In addition, they avoided a carbon dioxide emission of seven thousands kilograms.

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The verdict

– We endorse Swedish Hydro Solutions and spread the knowledge of their treatment solution internally. The solution is simple, smooth and clean very well. And they are very knowledgeable, responsive, helpful and service minded.
– Åsa Wetterberg, Jernhusen

They managed to remove all drilling mud from the water, so it became crystal clear. We succeeded in following Gothenburg’s high demands – the water furthermore became significantly cleaner than the guideline value.

Åsa Wetterberg

Construction Project Manager, Jernhusen

Treatment results

Suspended material, mg/l

  • Site specific guideline value (40 mg/l)
  • Untreated water (7800 mg/l)
  • After chitosan treatment ( 31 mg/l )


  • Guidline value, City of Gothenburg (15 µg/l)
  • Krom i orenat vatten (531 µg/l)
  • After chitosan treatment (1,1 µg/l)


  • Guideline value, City of Gothenburg (40 µg/l)
  • Nickel in untreated water (355 µg/l)
  • After chitosan treatment (2 µg/l)

Need more information?

Carl-William Kalholm - sales coordinator

+46 723 05 80 85

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