Effect of Nitrogen Load and Water Temperature on Nitrification Efficiency of Nitrification Tank Using Submerged Bed Process.

Synthetic inorganic NH4-N wastewater with a load of 0.06, 0.12 and 0.24g/l·d were drculated through a nitrification tank equipped with a lace-like contact medium. At water temperatures of 20 and 30°C, high nitrification efficienaes (more than 90%) were obtained irrespective of the loading condition. At a water temperature of 10°C, a nitrification efficsency of approximately 80%was obtained under a low loading condition of 0.06 g-NH4-N/l⋅d. The maximum nitrifcation rates were 22.6mg-N/g-VSS·hr at a water temperature of 30°C, 11.0mg-N/g-VSS·hr at a water temperature of 20°C and 6.2mg-N/g-VSS·hr at a water temperature of 10°C.Temperature coeffiaents (θ) for nitrification were calculated to be 1.023-1.084.As the NH4-N loading rate was lowered, the influence of water temperature on nitrification effiaency was smaller. These results show that the nitrogen load should be limited to 0.06g/l⋅d or lower for nitrification treatment using the submerged bed process at a low water temperature.