| To traditional nitrification and denitrification sewage denitrification process, the low C/N wastewater will not be able to treated, with discovering and the development of some new type of autotrophic denitrification process, this shortcoming will be overcomed. The Completely Autotrophic Nitrogen Removal Over Nitrite(CANON) process can not only treat the low C/N wastewater, but also has the advantages of less land occupation, simple technology, economy, energy conservation and environmental protection, so the process has attracted many attentions of the scholars at home and abroad.In this study, synthetic wastewater was used and the CANON process was started up by using activated sludge process, the recovery method of CANON process on the brink of collapse was discussed, the influence of aeration ratio on CANON process was studied, orthogonal experiment was designed to explore the best conditions of nitrogen removal performance of CANON process, the activity of Ammonium Oxidation Bacteria(AOB), Anaerobic Ammonia Oxidation Bacteria(AAOB), Nitrite Oxidizing Bacteria(NOB) was determined in this system.Conventional activated sludge was inoculated in a sequencing batch reactor(SBR) to explore the start-up of CANON process. The results showed that when the short-cut nitrification process was stabled, inoculating with about 0.15 g biofilm with function of autotrophic nitrogen removal, the CANON system was successfully launched within 113 days. The total nitrogen removal rate and the volumetric loading rate reached 85.52% and 0.28 Kg N/(m3ï¹'d), respectively, and 83.07% and 0.422 Kg N/(m3ï¹'d) were reached after improving the loading respectively. The start-up period was remarkably shorted by inoculating with about 0.15 g biofilm with function of autotrophic nitrogen removal. In addition, during the period of stating-up CANON prcess, there was a tendency on sludge granulation.During the operation, the concentration of nitrate nitrogen increaseed too high due to excessive aeration, and the denitrification performance of CANON system decreased seriously, by taking method of controlling aeration rate and the concentration of Free Ammonia(FA), the activity of CANON system is restored successfully. The research results show that to recovering a CANON systerm on the brink of collapse that because of excess aeration, we can raise the concentration of influent ammonia nitrogen by first, and then reduce aeration rate. At this research the concentration of influent ammonia nitrogen is from 400 mg/L to 700 mg/L, and reduce aeration rate when the concentration of nitrate changed little in effluent. By the output of NO3- and NH4+ removal ratio as an index which can reflect the denitrification performance of CANON system, after 15 d, the output of NO3- and NH4+ removal volume ratio achieved a better level, after 22 d system is restored successfully. Remove load reached 0.463 Kg N/(m3·d), higher than that of before 0.355 Kg N/(m3· d).The CANON system performance under two aeration mode: intermittent aeration and continuous aeration was compared. A aeration mode both economical and is advantageous to the SBR activated sludge process of CANON system was explored. Under the way of intermittent aeration and aeration/non-aeration ratio of 0.5 h:1 h, 1 h:0.5h and 1 h:1 h was studied. The results show that, the mode of intermittent aeration more conducive to the stability of CANON system. And when aeration/non-aeration ratio is 1h:1h, the nitrogen removal load is the highest, reached 0.470 Kg N/(m3 · d).Based on orthogonal experinment, the effect of oxygen(DO), the initial concentration of NH4+-N, p H and temperature(T) of CANON system was dissolved. The variance analysis results show that at the given level of significance of alpha = 0.1, and within the scope of selected conditions NH4+-N(100 ~ 300 mg N/L), T(25 to 38 ℃), p H(7.5 ~ 8.8), DO(0.1 ~ 0.3 mg/L), p H has a marked effect on total nitrogen removal rate and anaerobic ammonia oxidation rate, the factors of NH4+-N and DO effect anaerobic ammonia oxidation rate prominently, the influence of the DO concentration on nitrite oxidation rate is significantly. Adopt the method of grade comprehensively obtained the best experimental conditions for NH4+-N: 200 mg/L, T: 31 ℃, p H: 8.2, DO: 0.1 mg/L. |
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