EFFECT OF TEMPERATURE AND DISSOLVED OXYGEN CONCENTRATIONS ON THE NITRITATION IN A SUBMERGED BIOFILTER

This experimental study focused on the effects of DO concentrations and temperature on the ratio of NO2-N/NOx-N and NH4-N removal efficiency in the submerged biofilter. The highest NO2-N/NOx-N ratio was achieved at the temperature of 350C. At the DO concentrations of 4.5 mg/L, the removal efficiency of NH4-N and NO2-N/NOx-N ratios were about 91% and 0.52, respectively. Decreasing the DO concentration to about 4.0 mg/L, the removal efficiency of NH4-N dropped to 73%. However, the ratio NO2-N/NOx-N increased to about 0.62. Increasing the DO concentrations at the top of the biofilm reactor, enhance the activity of nitrobacter species and NO2-N was further oxidized to NO3-N. The highest NO2-N production (0.386 Kg NO2-N/m3.day) and NH4-N removal rate (0.750 Kg NH4-N/m3.day) were obtained at the DO concentrations and temperature 4.0 mg/L and 350C, respectively.