This latter was obtained from the hydrolysis of local date stones. The total thickness of the filter media was 60 cm. The height of the resulting bed ranged from 0 to 24 cm, and was controlled by adding only activated carbons. The efficiency of the filtration system was evaluated by monitoring the time-courses of COD and BOD5 values, as well as their evolution over the height of the bed. The comparison of these results to those obtained with a bed of sand dune only showed a clear enhancement of the efficiency which lay between 80-95 (%) for COD and 78-94 (%) for BOD5