Knarrdalstrand avlopsrenseanlegg - Porsgrunn Wastewater Treatment Plant, Norway

Knarrdalstrand avlopsrenseanlegg is a wastewater treatment plant located in Porsgrunn, Telemark, Norway. Serving a population of approximately 50,000, it is a key component of the region's municipal wastewater infrastructure. The plant is situated in the coastal town of Porsgrunn, which lies along the Porsgrunn River estuary. As a Norwegian plant serving a medium-sized agglomeration, it operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which Norway implements through its national regulations. For populations between 10,000 and 100,000, the directive requires secondary treatment as a minimum, with more advanced treatment in sensitive areas. The plant's designed capacity is 1.00 (likely in thousands of cubic meters per day or similar unit), indicating it is sized to handle the local load. The treated effluent is discharged into the Porsgrunn River, which flows into the Frierfjord and ultimately the Skagerrak strait. This water body supports diverse aquatic life and is important for local fisheries and recreation. The plant's operation helps protect the fjord ecosystem from nutrient pollution and pathogens.

The plant discharges into the Porsgrunn River, which flows through the Frierfjord and into the Skagerrak, a strait connecting the North Sea to the Baltic Sea. This coastal watershed supports diverse marine life, including fish stocks and benthic communities. Effective treatment is essential to prevent eutrophication and maintain water quality in the fjord, which is used for recreation and commercial fishing.