DEREHAM STW - Breckland, Norfolk Wastewater Treatment Plant

DEREHAM STW is a wastewater treatment plant located in Scarning, near Dereham, in the Breckland district of Norfolk, England. It serves a population of approximately 21,701 people, classifying it as a medium-sized agglomeration under UK and EU regulatory frameworks. The plant is situated inland, over 50 km from the coast, and its operations are integral to managing municipal wastewater in this rural area of East Anglia. As a UK wastewater facility, DEREHAM STW operates under the Urban Waste Water Treatment Regulations (transposing the EU Urban Waste Water Treatment Directive 91/271/EEC). For a population equivalent of this scale, secondary treatment is typically required, with additional nutrient removal if discharging into sensitive areas. The treated effluent from DEREHAM STW is discharged into local watercourses that feed into the River Wensum, a chalk stream of high ecological importance. The Wensum flows through Norfolk and eventually reaches the North Sea via the Great Ouse system or directly through the Norfolk Broads. This catchment supports diverse aquatic life, including salmonid fish and rare invertebrates, making effective wastewater treatment essential for maintaining water quality and biodiversity.

DEREHAM STW discharges into the River Wensum catchment, a designated chalk stream known for its clear waters and rich biodiversity. The Wensum flows into the River Yare and then to Breydon Water, an estuary that connects to the North Sea. This watershed supports species such as brown trout, water voles, and various dragonflies. The plant's operations help protect these ecosystems from nutrient pollution and other contaminants, particularly given the sensitivity of chalk streams to eutrophication.