Nitrogen and bacterial removal in constructed wetlands treating domestic waste water Original Research Article

The current study was carried out to compare the performances of two combined systems at pilot scale: the first one is composed of a vertical flow bed planted with Phragmites and a horizontal flow bed planted with Typha. The second combined system is an unplanted one. Each vertical flow bed, placed in the upstream of the horizontal flow bed is fed intermittently with a flow rate of 0.144 m3 per day corresponding to an hydraulic application rate of a 0.24 m3/m2/day. Such parameters as Kjeldahl nitrogen, ammonia, and nitrate, nitrite, total and faecal coliform in the influent and effluent of the wetland system are examined, and their removal rates are determined. Nitrogen removal in planted system was greater than in unplanted one especially for nitrogen Kjeldahl (27 and 5%) and nitrogen ammonia (19 and 6%). Whereas, removal of nitrate-nitrite in planted system is less than in unplanted one (4 and 13%). However, bacterial removal in both planted and unplanted system was similar.