Performance Assessment of an Integrated Constructed Wetland-Pond System in Dublin, Ireland

John Stack, Yaqian Zhao



The concept of the Integrated Constructed Wetland (ICW) differs from other types of constructed wetlands (CWs) in that ICW systems take a multi-disciplinary approach to treating wastewater, aiming to optimise landscape fit and enhance biodiversity. This study reports a technical assessment of an ICW-pond system at Tolka Valley Park, Finglas, Dublin 11, Ireland, to treat the feedwater to an ornamental pond in a public park. Monitoring data has indicated performance issues within the ICW-pond system, as concentrations of ammonia at the outfall from the pond to the River Tolka were higher than that at the inlet to the system. The pond has also been subject to a severe algal bloom in the summers of 2010 and 2011. This technical assessment has demonstrated the role of barley straw to control the algal bloom in the pond. In addition, groundwater monitoring around the pond has indicated that leachate from a nearby landfill may be leaking into the pond, thus causing the increase of nitrogen in the pond and in the effluent from the system. The purpose of this technical assessment was to identify the underperformance issues of the system, determine the effectiveness of barley straw in controlling algal blooms in the pond and, accordingly, some recommendations to improve the system performance have been presented at the end of the paper. The research demonstrated that the landfill is, in fact, impacting on the pond and causing the system’s underperformance and that barley straw can be effective in controlling or inhibiting algal blooms.


Keywords: Integrated constructed wetland; technical assessment; performance; wastewater treatment; Ireland