[Realization of Short-cut Nitrification in a CAST Process at High Temperature and Its Phosphorus Removal Performance].

A synthetic wastewater was employed to investigate the realization of short-cut nitrification and its phosphorus removal performance in a CAST reactor operated at 22℃, 25℃, and 28℃. The results showed that TN removal of the system was stable and higher than 80% at different temperatures, and NH-N removal performed well. When the temperature was at 22℃ and 25℃, nitrite accumulation was not observed in the system and the phosphorus removal rate were 94.3% and 86.9%, respectively. When the temperature was increased to 28℃, nitrite accumulation efficiency in the reactor reached 87.2%, implying the system achieved a stable short-cut nitrification. In addition, in the short-cut nitrification stage at high temperature (28℃), the phosphorus release and uptake capacity of the system decreased. The anaerobic phosphorus release/COD consumption (P/C) ratio was much lower compared those at 22℃ and 25℃. However, the phosphorus removal performance of the reactor did not deteriorate at this stage. The phosphorus removal rate was 68.9%, indicating that a sufficient carbon source in the influent could not only guarantee the removal of TN, but also detoxify NO to reduce its inhibitory effect on the phosphate accumulating organisms (PAOs). The batch tests of phosphorus uptake by the sludge under different temperature conditions revealed that O, NO, and NO could all be used as electron acceptors for phosphorus uptake. The aerobic phosphorus uptake rate was higher than that with NO and NO as electron acceptors. The phosphorus uptake rates of O and NO as electron acceptors were also found to be negatively correlated with temperature.