Evaluation of plant efficiency in a constructed wetland receiving treated tannery wasterwater.

A free water surface pilot-plant was constructed with the aim to reduce the high concentrations of sulfate, sodium, chloride and chromium in treated tannery wastewater. The CW was composed of two cells, one planted with Phragmites australis and the other with Carex ssp. Plants were sampled monthly to evaluate the effects of wastewater on growth and the accumulation of Cr, S, Na, Cl in different plant organs. No effects of the wastewater quality on fresh and dry weight of plants and on leaf pigment content were observed. Accumulation of cromium, sulfur, sodium and chloride was higher in roots than in shoots of both plant species. Mean Cr and S contents were recorded to be higher in P.australis plants (74.3 µg g-1 d.w. for Cr, 16.9 mg g-1 d.w. for S).than in Carex ssp. plants (16.2 µg g-1 d.w. for Cr, 12.1 mg g-1 d.w. for S). Carex ssp. plants accumulated more Na (17.4 mg g-1 d.w.) and Cl (22.7 mg g-1 d.w.) than P.australis ,12.6 mg g-1 d.w. and 18.7 mg g-1 d.w., respectively. P.australis plants seem to be more suitable for removal of pollutants from the tannery wastewater, due to the greater biomass produced.