Performance evaluation of integrated constructed wetlands treating domestic wastewater

The performances of a new and a matureintegrated constructed wetland (ICW) system treatingdomestic wastewater were evaluated for the first time.The new ICW in Glaslough (near Monaghan, Ireland)comprises five wetland cells, and the mature systemin Dunhill (near Waterford, Ireland) comprises fourcells. The performance assessment for these systemsis based on physical and chemical parameters collectedfor 1 year in Glaslough and 5 years in Dunhill. Theremoval efficiencies for the former system wererelatively good if compared to the international literature:biochemical oxygen demand (BOD, 99.4%),chemical oxygen demand (COD, 97.0%), suspendedsolids (SS, 99.5%), ammonia nitrogen (99.0%), nitratenitrogen (93.5%), and molybdate-reactive phosphorus(MRP, 99.2%). However, the mature ICW had removalefficiencies that decreased over time as the Dunhillvillage expanded rapidly. Themean removal efficiencieswere as follows: BOD (95.2%), COD (89.1%), SS(97.2%), ammonia nitrogen (58.2%), nitrate nitrogen(−11.8%), and MRP (34.0%). The findings indicatethat ICW are efficient in removing BOD, COD, SS,and ammonia nitrogen from domestic wastewater.Moreover, both ICW systems did not pollute thereceiving surface waters and the groundwater