[Carbon and Nitrogen Removal Characteristics of ABR Decarbonization-CANON Coupling Process]

If municipal wastewater can be treated by the completely autotrophic nitrogen removal over nitrite (CANON) process, it will greatly reduce the energy consumption of municipal wastewater treatment. The CANON reactor with a fiber carrier was started up by seeding nitrosation sludge and anaerobic ammonia oxidation (ANAMMOX) sludge in the continuously stirred tank reactor (CSTR). An ABR decarbonization system was added to the front of the CANON system to build the ABR decarbonization-CANON coupling process to examine carbon and nitrogen removal characteristics of the whole system. The high throughput sequencing technology of MiSeq was also employed to analyze the structure of the microbial community before and after the reactivation. The results showed that mixing nitrosation sludge and ANAMMOX sludge in the CSTR reactor under controlled parameters (DO of 0.5-2 mg·L^-1; HRT for 6 h; pH of 8) allowed the CANON system to successfully start within 55 d, with a TN removal rate of 81%-87% and ammonia nitrogen load of 0.195 kg·(m³·d)^-1. The effluent COD concentration of the ABR decarbonizing system did not adversely affect the subsequent CANON system, and the TN removal rate of the ABR decarbonization-CANON process was between 74% and 87%. Additionally, the average concentration of COD in the effluent was 40 mg·L^-1. At the same time, the Proteobacteria gate significantly improved after the CANON system began, and the proportion of Sphingobacteria decreased to 6.8%. Nitrifying bacteria and anaerobic ammonia oxidizing bacteria in the CANON system continuously eliminated the inferior bacterial groups to become the dominant group in the reactor. The integrated ABR decarbonization-CANON process had a positive effect on the denitrification and decarbonization of urban sewage.

[A New Model for the Treatment of Low Ammonia Nitrogen Wastewater by CANON Process]

Automatic aeration and recirculation of effluent were used to start CANON process with up flow sludge bed reactor, and the start-up and operation characteristics of the process were studied. The results showed that the CANON process could be started quickly and stably by the method of reoxygenation reflux under the conditions of sludge volume fraction 25%, NH₄⁺-N 157 mg·L^-1, HRT 2 h. After 50 days of operation, the total nitrogen removal rate increased from 1.31 kg·(m³·d)^-1 to 1.47 kg·(m³·d)^-1; the reoxygenation reflux manner could effectively control the amount of dissolved oxygen in the reactor, resulting in DO<0.01 mg·L^-1, which had a good inhibitory effect on the NOB in the system, and meanwhile provided a good growth environment for AnAOB; By controlling the reflux flow, the production rate of NO₂^- could be precisely controlled, reaching a good balance with NO₂^- consumption rates, and thus avoiding the accumulation of NO₂^- and occurrence of nitration reactions. Therefore, reoxygenation reflux CANON process showed a great advantage in the operation stability, which provided a new model for the start-up and stable operation of CANON process.