| Accumulation of ammonia nitrogen in the water environment will seriously deteriorate water. Ammonia is one of the main factors for eutrophication. Therefore, effective ammonia removal is present hotspots. Compared to conventional biological nitrification-denitrification process, new biological nitrogen removal reduces energy consumption through controling nitrification process to nitritation and eliminating the further oxidation process of nitrite to nitrate in traditional biological nitrogen removal and achieves the accumulation of nitrite successfully. How to control the nitrification process to achieve nitritation stage of the accumulation of nitrite is the key of realizing the combination of shortcut nitrification. Ammonium-oxidizing bacteria were cultivated by controlling the substrate concentration and reactor operating conditions. Different substances impact on the ammonia oxidation process was studied under the action of granular sludge. Non-substrate inhibition kinetic equation was established for the inhibition effect of free nitrous acid. Soluble microbial products of ammonium-oxidizing bacteria were discussed to provide basis for the characteristics of ammonia oxidation process. Main research's result as follows:1. Mature granular sludge was brown, lighter in color, and its diameter was between 0.4-3.5mm. It was sensitive to temperature. The activity of bacteria was significantly decreased at low temperature (in winter) as the optimum temperature of 20-30℃, while the biological activity was higher in summer. 2. SBR reactor used to cultivate granular sludge operated stably. Ammonia degradation rate reached 90%, and NO2-N has been accumulated effectively which its content reached 95% of total NOx-N.3. The reaction rate of ammonia oxidation bacteria enriched granular sludge was positively correlated with the comcentration of inorganic carbon. Without carbon source, microbial activity was seriously inhibited, virtually no degradation of ammonia, but increasing the concentration of carbon, the reaction rate improved thereupon. When NaHCO3 was added as 0g, 1.2g, 2.4g and 3.6g with the substrate concentration of NH4+-N 150mg/L, NH4+-N degradation rate was 1.2%, 36.3%, 73.6% and 92.5% respectively.4. Organic matter in the substrate had some influence on the reaction rate of nitrosation. The reason probably was that the activity of heterotrophic bacteria increased in the presence of organic matter. 5. Free nitrous acid formed from nitrite inhibited nitritation reaction. The results shows that the higher nitrite concentration, the stronger inhibition of nitritation. The establishment of non-substrate inhibition equation obtained that the free nitrous acid inhibition constant was 0.0373mgHNO2-N·L-1, less than floc sludge system inhibition constant. It indicated that the system of AOB enriched granular sludge was easier inhibited by FNA.The research shows that nitrate concentration has little effect on the nitrosation reaction rate.6. Observed concentration changes of soluble microbial products and found that it showed upward trend in concentration only the nitrogen and inorganic carbon in the substrate. In this system, soluble microbial products production is not much, usually only about 10mgCOD/L.
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