Excess water from waste, rainfall and drainage is collected in a water reservoir in Langøya. From here, the water is pumped up to a buffer tank, where it is distributed between processing plants for waste treatment and water purification plants. From the water purification plant, the water is pumped into the sea within the emission limits stipulated in the permit from the Environment Agency.
The water purification plant consists of two purification steps. In the first step, purification chemicals are added for clearing heavy metals into a separate pool. In the second step, the water is pumped from the pool to a sand and coal filter, which removes the remaining particles and any loose organic remnants. From the filter plant, the water is pumped to the sea while the water volume, pH and turbidity (particle content) is constantly checked.
Tests are regularly performed for emission checks. The tests are analysed internally at NOAH’s own laboratory as well as in the externally accredited laboratory. The sea emissions are checked according to the emission permit from the Environment Directorate. Between 600,000 – 800, 000 m3 of purified water is pumped into the Holmestrand Fjord annually.