MOSTYN STW - Secondary Wastewater Treatment Plant in Mostyn, Wales

MOSTYN STW is a wastewater treatment facility located in Mostyn, Flintshire, Wales, near the A548 road. The plant serves a population of around 4,293 people and is situated close to the Dee Estuary, an important coastal and estuarine environment. As a secondary treatment plant, it provides biological treatment to reduce organic pollutants before discharge. The plant has a designed capacity of 4,620 m³/day and currently discharges an average of 955.77 m³/day of treated wastewater. Under the UK's implementation of the EU Urban Waste Water Treatment Directive (UWWTD), secondary treatment is the standard requirement for inland and coastal discharges from agglomerations of this size. The plant's location within 10 km of the coast means it must meet additional standards to protect sensitive marine environments. The treated effluent from MOSTYN STW enters the Dee Estuary, which flows into the Irish Sea. The Dee Estuary is a site of ecological importance, supporting diverse bird populations and marine life. The plant's operation helps maintain water quality in this sensitive coastal ecosystem, balancing the needs of the local community with environmental protection.

MOSTYN STW discharges into the Dee Estuary, a major coastal inlet that flows into the Irish Sea. The estuary is a dynamic environment supporting migratory birds, fish, and intertidal habitats. The plant's secondary treatment ensures that nutrient and organic loads are reduced before entering this ecologically sensitive area, helping to prevent eutrophication and maintain biodiversity in the downstream marine ecosystem.