Analysis of the reclamation treatment capability of a constructed wetland for reuse

A research project was conducted during 2008-2009 in Portugal to evaluate the potential of reclaimed water from constructed wetlands for irrigation reuse. A 21 month monitoring campaign was set up in a Filtralite-based horizontal subsurface flow bed. Results showed a significant fluctuation of the hydraulic loading rate that has influenced the hydraulic retention time and the wastewater characteristics over time and, therefore, the removal efficiencies for BOD5, COD, TSS, nitrogen and phosphorus were lower than the reported values for CW performance. If the hydraulic loading rate could be properly controlled the treatment performance, as well as the quality of the reclaimed water, can be improved considerably. The effluent concentrations of conductivity (EC), BOD5, COD, TN, K, Ca, Mg and phytotoxic elements (Na, Cl and B), showed a suitable quality for irrigation reuse according to different international standards, although it is necessary to improve the removal of phosphorous and a final disinfection must be implemented to decrease the pathogenic content.