Granulation Of Deammonification Microorganism In SBR Reactor

Accumulation of ammonia in water environment has induced serious deterioration to the quality of water environment. It is a problem that should be solved by using proper measure to prevent the deterioration without delay. Wastewater with high nitrogen concentrations and low C/N ratio are rather cost-intensive when treated with conventional concepts, as both the oxygen demand for nitrification and the demand for organic substrates for denitrification depend on the respective nitrogen concentration in the wastewater. It goes against the sustainable development of wastewater treatment. Recently a new process named as deammonification, which describes the oxidation of nearly 50% of the NH4+ to NO2-and subsequent conversion of NH4+ and NO2- to molecular nitrogen (N2 gas). The main advantages of these process is lower oxygen demand (up to 25% energy savings during aeration) and reduced 40% organic substrate requirements for heterotrophic denitrification, so it become the highlight in the biological de-nitrogen study.Based on the latest research findings on biological nitrogen removal in both domestic and abroad, the influence of inorganic carbon concentration, pH value and dissolved oxygen (DO) in deammonification was studied in a SBR reactor using biofilm possessing deammonification action as the inoculation. In order to investigate the possibility of the granulation of deammonification bacteria, normal activated sludge and aerobic granular sludge were seeded in another two laboratory scale SBR reactors (Rl, R2) respectively.The experiment results showed that the NaHCO3 concentration increased from 1.75g/L to 2.5g/L, the pH value in the reaction system increased from 7.6-8.0 to about 8.8, the conversion rate of ammonium nitrogen and total inorganic nitrogen removal rate all decreased dramatically to 53% and 48.8% respectively. Dissolved oxygen is an important factor effecting on the deammonifictian process. So it should be adjust with the influent ammonia concentration. When the ammonium-nitrogen load of input water was 60g/(m3-d), the best DO concentration should be controlled at 0.5~0.7mg/L. Under these conditions, the conversion rate of ammonium-nitrogen reached higher than 90%.Through the research on the granulation of deammonificatin bacteria, we found in the course of accumulation adding trace amount of hydroxylamine could accelerate the nitritation. Nitrite began to accumulate from the third week in both reactors. But...