[Effect of Free Nitrous Acid on the Activity of Nitrifying Bacteria in Different Sludge Concentrations Under Anoxic Conditions].

This study investigated the inhibitory effect of free nitrous acid (FNA) on the activity of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) under anoxic conditions with different mixed liquid suspended solids (MLSS). Sequencing batch reactors were used to study the changes in the activity of AOB and NOB in nitrifying activated sludge based on four different MLSS (8398, 11254, 15998, and 19637 mg·L), after treatment, under anoxic conditions with FNA (at an initial concentration of 1.3 mg·L) for 48 h.

[Stability of the CANON Process Based on Real-Time Control Technologies].

In order to achieve the optimization of the CANON process, ensuring the stability of water quality and increasing the removal rate of ammonia nitrogen, the stability of CANON process water quality under real-time control was studied in the SBR reactor. During the experiment, the temperature was controlled at 30℃±1℃ and the pH was 7-8, based on the corresponding relationship between indirect parameters and nitrogen pollutants, the real-time control strategy was formulated. The results showed that when the influent ammonia nitrogen concentration was 917-1540 mg·L, the residual ammonia nitrogen concentration of 6 mg·L can be used as the control parameter to meet the requirements of process stability but the ammonia nitrogen sensor had many problems such as high costs and large errors.

[Start-up of Granule CANON Process and the Strategy for Enhancing Total Nitrogen Removal Rate].

To shorten the start-up time of the CANON granular sludge process and improve the total nitrogen removal rate in the engineering, the start-up method of CANON granular sludge process and the strategy for enhancing the total nitrogen removal rate were studied in an SBR reactor. During the experiment, the temperature was controlled at 30℃±1℃ and the pH was 7-8, the aeration rate and settling time were operated according to the sludge properties and effect of nitrogen removal. The results showed that the transition of the sludge properties from combined floc-granule to granule was realized after 55 d.

[Start-up of Combined Floc-granule CANON Process and the Effects of SRT on Reactor Performance].

To shorten the start-up time of CANON process and guide the sludge dischargement in the practical project, the start-up of CANNON process and influence of different flocs SRT were studied by inoculation ANAMMOX granules of different proportions in two same specifications of SBR reactor. During the experiment, the temperature was controlled at 30℃±1℃ and pH was 7-8. The results showed that it was not good for CANON process rapid start-up when the two reactors were inoculated with 5% and 10% ANAMMOX granules respectively and the initial FA concentration exceeded 44 mg·L.