Nitrifying biofilter: Synthetic wastewater prepared in 100
L tank from ammonium chloride (NH4Cl) at concentration of
100 mg-N/L was used in the experiment and sodium
hydrogen carbonate (NaHCO3) was added in to increase the
total alkalinity to 300 mg CaCO3/L. Then plastic media was
added at a ratio of 1:3 (v/v) media to water. The optimum
activity of microorganism fixed on the support media
biofilter would be observed until the concentration of
ammonia and nitrite were less than 1 mg-N/L and nitrate was
not less than 10 mg-N/L.
Denitrifying biofilter: Synthetic wastewater prepared in
100 L tank from potassium nitrate (KNO3) at concentration
of 100 mg-N/L was used in the experiment and 100 g sucrose
was added to eliminate dissolved oxygen concentration to
less than 0.5 mg O2/L. Then, plastic media were added in
ratio of media to water 1:5 (v/v) and a complete mix inside
the denitrification tank was achieved with a propeller at a
speed of 100 rpm. The optimum activity of microorganism
fixed on the biofilter would be observed until the
concentration of nitrate was less than 1 mg-N/L.