A pilot unit was constructed and operated to study the ability of treating polluted water
using biological treatment. The experimental unit consists of water sprayer unit that ensure
wetting of the filtered media and distributing water in a homogen
ous manner as well as
increasing the dissolved oxygen concentration in water. The sprayer unit is followed by a
biological filter; the area of the filtered media was (13) m2. The developed biological film
placed on the filtered media will dismantle the organic matter, which reduce nitrates to
nitrite then to a nitrogen gas. The filter was connected to an aeration basin where the
suspended growth was archived. The pilot unit was operated depending on the water was
taking from a manhole nearby the residential unit number 18. The average efficiency of
BOD5 removing was 69.4% and of nitrate, removing was 34%. The results showed that
this system can improve water's characteristics.