Filtralite - Leca Norge As

Filtralite for Norway’s largest ozonation/biofiltration potable water treatment plant.


Source: Filtralite - Leca Norge As

Skien Municipality in southern Norway has chosen to use Filtralite as a bio-carrier in the biofilters when they rebuild Steinsvika Water Treatment Plant into an ozonation/biofiltration process.

Steinsvika WTP will have a max production capacity of 1650 m3/h (39 600 m3/day) and a normal production of 650 - 1250 m3/h (15 600 – 30 000 m3/day). A total of 550 m3 of Filtralite will be supplied to the plant during November 2009. The plant will be in full operation by the end of February 2010.

The raw water of the plant is taken from the lake Norsjø. Most of the year the water is of good quality, but during shorter periods, and if there are a flood in the lake and connected rivers, the water is of less good quality. The water temperature will over the year vary between 2.5oC and 5oC. The main issue for the treatment process is removal of Natural Organic Matter (NOM) that gives colour to the water and to ensure good hygienic barriers.

The NOM-/colour removal will be done by dozing of ozone at the inlet of the plant, after first dosing CO2. The ozone breaks up the large NOM molecules into smaller molecules that are easily biodegradable. It also kills any micro organisms that might be in the water and increases the UV transmission of the water, so that the UV disinfection will be more effective. After the ozone is added, it reacts with the water in a reaction chamber with 10 minutes contact time at Qmax. After the reaction chamber the water flows through calcium carbonate filters to optimise the pH and to remove rest ozone before the water comes to the biofilters. In the biofilters bacteria will use the organic molecules produced in the ozonation process as “food”. These filters are filled with Filtralite, which with its high porosity provides a large surface area where the bacteria can colonize. In the bottom of the biofilters there will be a layer of sand that will act as a polishing layer to control the turbidity level. As a final step the water is disinfected, first by UV light and finally with chlorination.

Filtralite at exhibitions

Filtralite will be present at the following exhibitions during the first half of 2010:

  • Everything About Water, Chennai, India, 7-9 January 2010
  • IFAT China, Shanghai, China, 5-7 May 2010

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