Danish Water Technology

It has always been our ambition in Denmark to find and develop better, cheaper and more efficient ways to handle drinking water and wastewater.

Feel free to look around and get inspired by some of our Danish state-of-the-art technologies for water solutions - Welcome to Future Water City

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HOFOR

Calcium
Removal Plant

Softening system to remove
calcium from drinking water

A softening pilot plant has been developed in order to do pre-design assessment of the impact of installing full-scale pellet reactors for calcium removal. Hereby it is possible to optimize design with respect to calcium removal as well as other unwanted substances in the water.

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The Challenge

Water with large concentrations of calcium carbonate – or limescale – has always been a challenge, and consumers, politicians and industry alike have demanded effective methods for softening water for decades. Substantial benefits would be gained from such solutions particularly in the fields of energy and welfare technologies.

Impact and benefits

HOFOR (Greater Copenhagen Utility) has developed the Calcium Removal Plant. This solution has the potential for creating dramatic changes in the environmental impact of water supply and wastewater treatment.

  • A 50% reduction of household detergents.
  • No calcium carbonate sedimentation – or limescale – which means improved durability of water heaters, pipes and fixtures.
  • Reduced heat loss in hot water tanks and household appliances.
  • Improved durability of household appliances.
  • Better protection against bacteria and undesired metals in the water.
  • And last but not least a considerable reduction in the amount of phosphorus discharged to wastewater treatment plants.

The proces

Untreated water is mixed with fine sand and an alkali in a pellet reactor, causing the calcium to bind to the grains of sand.

The tiny balls of calcium-covered sand settle at the bottom of the tank and are removed and replaced with clean sand. The decalcified water is passed through a sand filter as the standard treatment before it is introduced into the distribution system. The result is soft water with a very low content of calcium.

An asset to society

The pellets can be used as chicken feed or as fertiliser in agriculture which means that this solution forms a circular economy – finding a use for everything.

The method will essentially provide better drinking water and improved consumer economy. The Calcium Removal Plant is an asset to society in general and to the environment in particular.

The Calcium Removal Plant has been developed by Greater Copenhagen Utility in collaboration with VCS Denmark and the Technical University of Denmark.