Blacklion

Background

The Blacklion Wastewater Treatment Plant (WwTP) in Co. Cavan is approaching the end of its design life and is currently unable to meet the Environmental Protection Agency (EPA) emission standards. An upgrade is essential to provide sufficient capacity for projected population growth while meeting regulatory discharge requirements.

The solution

The proposed design incorporates a two-stage reed bed treatment system, followed by a reactive media system for phosphorus (P) removal, replacing the existing process treatment assets.

  • Stage 1 – Reed Beds: Comprises four reed beds where solids are captured and dewatered on the surface. Wastewater then percolates through layers of sand and gravel before moving to the second stage.
  • Stage 2 – Aerated Saturated Vertical Flow Reed Bed: A single bed with forced aeration to enhance nutrient reduction. Horizontal flow beds are supplied with air using minimal energy to optimise treatment efficiency.
  • Stage 3 – Reactive Media Bed: A single batch-fed bed designed to remove residual phosphorus without the use of chemicals, power, or water, and producing no residual waste.

This system offers a low-energy, sustainable alternative to conventional wastewater treatment technologies and addresses the objectives of the WEST project by:

  • Improving treatment performance to meet EPA standards.
  • Delivering enhanced quality of effluent.
  • Minimising environmental impact through natural, sustainable processes.
  • Reducing operational energy demand and supporting net-zero carbon commitments.

Summary

This low maintenance sustainable solution will deliver enhanced effluent quality to achieve compliance with discharge standards. The installation will allow NI Water and Uisce Éireann to glean first-hand information on this innovative technology to inform future wastewater treatment projects. With a higher quality of effluent going to local waterways, tourism organisations will have increased confidence in promoting the Erne catchment for angling and water-based activities.