Water treatment performance and environmentat impact of integrated constructed wetlands in the Anne valley watershed, Ireland

Integrated constructed wetlands (ICWs) can provide a management option for the collection and treatment of farmyard dirty water. An integrated constructed wetland is a surface flow wetland, which mimics the role and structure of natural wetlands. It also encompasses elements of landscape fit, biodiversity and habitat enhancement into its design. As part of the Annestown stream restoration project, ICWs were installed to treat dirty water from 12 farmyards. A detailed monitoring programme was conducted between 2001 and 2004. A significant reduction in organic matter, nutrients and faecal indicator bacteria between influent and effluent samples was recorded. There was no summer discharge from any of the farm wetland systems. An improvement in the quality of the receiving water (Annestown stream) was observed. A site-specific study suggested that P exported from an ICW system was similar to background levels of P export rates from land to water. In general, the ICWs monitored during this study indicate that they are capable of treating farmyard dirty water to a satisfactory quality, thereby provide a means of reducing nutrient and contaminant loss from agriculture.