Abstract

In this paper three material with equal amount have been chosen to make a mixture, these materials are sand (passing sieve no. 1.18, porosity 0.41), activated carbon (passing sieve no. 4.75, porosity 0.51), crushed bricks (passing sieve no. 20, porosity 0.47), the mixture was used as a bio-filtering media , placed to a height of (1.15) m in a cylindrical filter with diameter of (300)mm and a height of (2)m which is designed and constructed from (PVC).
The filter is equipped with three piezometers fixed at three point along the height of the cylindrical filter, in addition to three overflows at different height, and an outlet with control valve.
On May 2010 the filter was operated with a synthetic wastewater similar to domestic sewage in order to determine the hydraulic and sanitary characteristics of the filter. Then the feeding of waste water was continued for 3 weeks in order to stimulate the growth of bio-film.
On June 2010 the filter was operated with gray water to determine the change in filter characteristics after the bio-film growth, and to evaluate filter efficiency to treat this water for the purpose of reuse.
The outcome of this work showed that the mixed media bio-filter, to a certain extent, is similar in hydraulic characteristics (pressure drop and hydraulic load) to granular activated carbon bio-filter, head loss at (1000) mm depth is (59%) of initial pressure, the growth of bio-film leads to increase in head loss by (43%), decrease in flow by (25|%), decrease in pressure by (16%).
According to removal efficiency of pollutants, the results shows an efficient removal of BOD‌5 (86%), turbidity (96%), TDS (81%) at a retention time (60 minute).