Purification Performance of Typha Latifolia, Juncus Effusus and Papyrus Cyperus in Arid Climate: Influence of Seasonal Variation

摘要

The purification of wastewater through the use of the plants (phytoepuration) was used in different areas and under various climates; it was tested successfully for organic pollution, for the elimination of phosphorus pollution, nitrogen pollution, metals, and for the destruction of the pathogenic germs. This study reports the monitoring of purifying performances of three plants, which show a good acclimatization in arid climate: Typha latifolia, Juncus effusus and Cyperus papyrus. The monitoring was carried out during one year from December to November in the southern Algeria. The experimental pilot set-up consists of four plastic barrels capacity of 130 L, filled from the bottom upwards to 45 cm thickness by gravel and 10 cm by sand, with opening located at 5 cm below the sand to avoid any overflow of water. Three barrels were planted with young stems of the studied species with the coverage of 36 stems/m(2), and the fourth barrel remained unplanted to serve as reference object. 30 L of wastewater which have undergone primary treatment at the purification station of Kouinine (north the town of El-Oued) was supplied to each barrel once a week. The flow occurred by percolation through the substrate. The residence time of water is 5 days. Treated water is recovered by a tap placed in bottom of the barrel. With the three tested plants, very satisfactory outputs were obtained for particulate and organic pollution, where the decrease rates of reached 96% for suspended matter (SM), 89% for the Chemical Oxygen Demand (COD), and 87% for the Biological Oxygen Demand (BOD5). The elimination of nitrogen and phosphorous pollution resulted in decreasing rates of 94% for nitrates and 95% for orthophosphates. The planted bed of Juncus effusus gives the best outputs for the elimination of organic and nitrogen pollution. However, the planted bed of Cyperus papyrus is the most appropriate for the phosphorous pollution. In addition, the elimination of the organic pollutants decreases in summer; never the less the output of purification remains higher than 68% for all seasons.