Research On High Concentration Ammonia Nitrogen Wastewater Treatment Process And Molecular Ecology

According to the properties of wastewater from food processing with high concentration ammonia nitrogen, SBR and packed bed bioreactor were developed for treating the high concentration ammonia nitrogen wastewater. Ammonia-oxidizing bacteria were isolated from SBR bioreactor. We were trying to understand the ammonia-oxidizing bacteria growth characteristics and culture conditions. Moreover, the ammonia-oxidizing bacteria populations distribution in the reactor were investigated. The main conclusions are as follows:1,In SBR bioreactor , when the influent concentration of ammonia nitrogen was 2500mg/L, the HRT was 48hours, pH was 7.5 and dissolved oxygen concentration was 1mg/L, the removal rate of ammonia nitrogen reached above 95%. And the bioreactor could maintain a high efficiency of nitrite process, more than 80% ammonia nitrogen was converted into nitrite. The effect of temperature on nitrite process was investigated by testing the system under 25-30℃, and we found that the effect of the temperature is negligible.2,In SBR bioreactor, under the condition of the influent concentration of ammonia nitrogen was 1000mg/L HRT 24h, pH 7.5 and dissolved oxygen concentration 3mg/L, ammonia nitrogen removal rate achieved 99% and more than 85% ammonia nitrogen was converted into nitrate. The content of nitrite was little. Active sludge sedimentation performance was well, sludge settling ration was 35-40, active sludge flocs particle size was 183.044μm.3,The packing bed reactor was inoculated with nitrite sludge. After two weeks, the biofilm was gradually formed on the plastic carrier. Under the condition of HRT 24hours, pH of 7.5, dissolved oxygen for the 3mg/L, ammonia nitrogen removal rate reached more than 99% and more than 75% ammonia nitrogen was converted into nitrite. The effect of temperature for the reactor was investigated by testing the bioreactor under 25-30℃, and the date showed that the effect of the temperature was negligible.4,Ammonia-oxidizing bacteria was isolated and purified from the sludge sample by streaking. Four strains of ammonia-oxidizing bacteria with relatively high degradation efficiency were successfully isolated. The growth conditions of one strain named GT-1 were investigated. The result showed that under the condition of 220r/min, temperature 30℃, pH 8.5, the ammonia nitrogen removal rate is highest.5,Ammonia-oxidizing bacteria population distribution was studied using TA cloning and restriction enzyme digest. The amoA gene from active sludge DNA was amplified, amoA gene library was constructed. Using the restriction enzyme we classify the bacteria to different genus. Through comparison of different genus's gene with the one that published in NCBI, we conclude that the majority of ammonia-oxidizing bacteria population was uncultured.