ARTIFICIAL WETLAND PERFORMANCES IN THE PURIFICATION EFFICIENCY OF HYDROCARBON WASTE-WATER

An artificial wetland planted with Typha latifolia was fed during a 36 0-day experiment with a reconstituted hydrocarbon wastewater (60 ppm, 850 L day(-1)). Concentrations and chemical composition were periodica lly monitored. The epuration efficiency was studied together with the accumulation in sediment and the bacterial development. The apparent e ffluent concentration was below 8 mg L-1 and the decrease in hydrocarb on concentration raised 90%. pH ranged between 6.9 and 8 and Total Sus pended Solids (TSS) were below 10 mg L-1. Hydrocarbon amount accumulat ed in sediment was estimated to be less than 10% of the input amount. We observed a high development of aerobic heterotrophic bacteria (10(6 ) bac mL(-1)) and hydrocarbon-utilizing bacteria (10(5) bac mL(-1)), w hich probably interacted with the plants for the biodegradation of hyd rocarbon (in the saturated effluent fraction, normal alkane biodegrada tion amounted to approximatively 80%). A comparative system with float ing plants (Lemma minor), named 'control bed', was studied in parellel and showed lower performances.