An assessment of the performance of willow evapotranspiration systems for the treatment of on-site wastewater in Ireland

Abstract

In Ireland, domestic wastewater from approximately 400,000 dwellings is treated by on-site systems which are all designed to distribute the treated effluent to groundwater via the subsoil on the site. Low permeability subsoils can result in lack of percolation and thus ponding of the effluent on the surface with potential surface water pollution around the site. In such cases, the only options available are discharge of wastewater to surface water (requiring a Water Pollution Act discharge licence, which local authorities are reluctant to grant) or installation of a zero discharge system. There is a reluctance in Ireland among local authorities to permit the use of zero discharge willow evapotranspiration systems as viable treatment systems given the lack of long-term performance data relevant to Ireland, or any information or guidance provided in the EPA wastewater treatment manual pertaining to the systems.