Skien Municipality in southern Norway is rebuilding 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). 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. The main issue for the treatment process is removal of Natural Organic Matter (NOM) that gives color to the water and to ensure good hygienic barriers.
The NOM removal will be done by adding ozone at the inlet of the plant. 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. In the biofilters bacteria will use the organic molecules produced in the ozonation process as “food”. As a final step the water is disinfected, first by UV light and finally with chlorination.
Ozone biofiltration is used around the world to remove organic matter not only for elimination of color, but also to reduce the formation of chlorinated organics that might result fromt eh reaction of chlorine with teh NOM.