The enrichment of the mixed ammonium oxidizers and their ammonium metabolic characteristics in the presence of O2 and trace NO2
The mixed ammonium oxidizer was enriched from the normal activated sludge in SBR, where the pH was controlled between 7.8 and 8.5, DO between 0.8 and 1.2 mgl -1 and temperature at 30±2 ℃. The experiment was carried out through synthetic wastewater, contained the initial NH + 4-N concentration of 50 mg l -1 and up to 250 mg l -1 gradually by the step of 50 mg l -1 . The MPN and MLSS test were run every 15 days to characterize the enrichment of ammonium oxidizers. The concentration of the mixed ammonium oxidizers increased by 300 times after the cultivation for 120 days. The results of batch experiment indicated that pH, DO and temperature had significant influence on the enrichment of aerobic ammonia oxidation bacteria. During the enrichment cultivation, pH, DO and temperature were the key factors, FA and nitrous acid could be properly controlled to inhibit the growth of nitrite oxidation bacteria, but not the ammonia oxidation bacteria. The ammonium metabolic characteristics of the enriched ammonium oxidizers under the atmosphere of O2 and trace NO2 were investigated in the lab-scale experiments. The results showed that the mixed ammonium oxidizer could use NO2 as electron acceptor to oxidize ammonium and produce NO when there was no molecule oxygen. The maximum ammonium oxidation rate was 0.063 mgNOD/(mgCOD·h) with 25ppm of NO2 present in the feed. The ammonium oxidation rate improved remarkably when adding a little amount of oxygen (2%O2) to the NO2 atmosphere. The maximum ammonium oxidation rate, 0.198 mgNOD/(mgCOD·h) occurred under the condition of the mixed gasses containing 2%O2 and 50 ppm NO2. Under the condition of mixed gasses containing 21%O2 and trace NO2, the ammonium oxidation rates further increased greatly. The maximum ammonium oxidation rate, 0.477 mgNOD/(mgCOD·h) occurred under the condition of 21%O2 and 100 ppm NO2 in the mixed gas, which is 3 times higher than the general aerobic ammonium oxidation rate. However, continuing to increase NO2 to 250ppm, the ammonium oxidation rate decreased on the contrary. NO2-dependent ammonium oxidation and aerobic ammonium oxidation of the mixed ammonium oxidizers could be well coupled with each other in the reactor.
Mixed ammonium oxidizers NO2-dependent ammonium oxidation O2-dependent ammonium oxidation Autotrophic nitrogen removal
Bo Zu Daijun Zhang Ping Zhang Liying Cong
Department of Resources and Environmental Science, School of River and Ocean Engineering, Chongqing Department of Environmental Science, Chongqing University, Chongqing 400030, China
国际会议
The 12th Asian Pacific Confederation of Chemical Engineering Congress(第十二届亚太化工联盟大会暨化工展览会)
大连
英文
2008-08-04（万方平台首次上网日期，不代表论文的发表时间）