2016 Volume 45 Issue 6 Pages 313-324
This paper addresses an approach to stabilize the performance of a nitrogen removal process in which the nitritation of ammonium proceeds simultaneously with the anammox reaction in a reactor with biofilm carriers after reducing the organic load of the influent in a high-efficiency solid-liquid separation system. A bench-scale continuous test was conducted using actual sewage at ambient temperature. The following findings were obtained : (1) Although the condition with a Kj-N load of ≥ 200 ㎎ N/(L carrier hr) is required to develop anammox newly while suppressing nitrite oxidation using only virgin carriers, the condition is not mandatory if a small amount of cultivated carriers is to be mixed with the virgin ones. (2) An excessive volumetric loading rate of influent organics may cause a deficiency in NO2-N formation, which in turn causes a decrease in the T-N removal rate. To prevent such an event, it is necessary to suppress the total organic carbon (TOC) volumetric loading rate to ≤ 9 ㎎ C/(L carrier hr) using a high-efficiency solid-liquid separation system. (3) If an excessive formation of NO2-N activates NO3-N formation, it takes a long time to inactivate the potential capability of nitrite oxidation even when NO3-N formation can be suppressed by increasing the Kj-N loading rate per carrier volume. Accordingly, it is essential to maintain the load rate of ＞ 200 ㎎ N /(L carrier hr) to ensure the stable performance of this process.
