Comparative pilot study of the performances of two constructed wetland wastewater treatment hybrid systems Original Research Article

For small settlements sanitation, constructed wetland systems offer a suitable social economic alternative to the classic wastewater treatment plants. In order to study the treatment mechanisms occurring in the soil–plant system, we set up a small-scale pilot wastewater treatment plant composed by a settler/digester followed by two trains combining two different types of subsurface flow constructed wetlands called ‘hybrid systems’. The first train represents a combination of a vertical flow reed (Phragmites australis) bed followed by a horizontal bed, planted with Typha, whereas in the second one, the combination is reversed. The hybrid systems are fed intermittently with a hydraulic load of 0.2 m per day given in two sequences of one hour separated by a six-hour rest period. We followed the quality of the effluent at the outlet of the beds. The two hybrid systems present satisfactory performances: yields higher than 90% in organic matter removal are registered.