A columnmade of Plexiglaswas used for biofiltration
experiments in this study. The column had an inner
diameter of 9.9 cm; a total height of 75cm and an effective
volume of 4 L (empty basis) and consisted of three stages. A
mixture of powdered compost supplied from Tehran compost
factory and lava (with the wet weight ratio of 2/1) acted as
packing material. The lava rubbles were semispherical with