LLANASA STW Wastewater Treatment Plant, Pen-y-ffordd, Flintshire, Wales

LLANASA STW is a wastewater treatment plant serving the community of Pen-y-ffordd in Flintshire, Wales, United Kingdom. With a population equivalent of around 31,500, it is classified as a medium-sized agglomeration under UK and EU regulations. The plant is situated near the coast, reflecting the region's coastal geography. As a UK facility, LLANASA STW operates under the Urban Waste Water Treatment Regulations, which transpose the EU Urban Waste Water Treatment Directive (91/271/EEC). For agglomerations of this size, secondary treatment is typically required, with additional nutrient removal if discharging into sensitive areas. The treated effluent from LLANASA STW is discharged into local watercourses that drain into the Dee Estuary and ultimately the Irish Sea. This coastal discharge point is ecologically significant, supporting diverse marine life and migratory bird populations. The plant plays a key role in protecting water quality in the region's sensitive coastal and estuarine environments.

LLANASA STW discharges into local streams that flow into the Dee Estuary, a major coastal inlet on the Irish Sea. The estuary supports a rich ecosystem of fish, birds, and invertebrates, and is an important migratory corridor for salmon and sea trout. The plant's location within 50 km of the coast means its effluent can influence nearshore water quality, necessitating effective treatment to protect marine life and recreational waters.