Nitrogen removal involving nitrification and denitrification was investigated in a fluidized bed bioreactor by using mixed culture sludge under oxygen-limited conditions. Methane was used as a sole carbon source for denitrification. In this study, optimal nitrification and denitrification rates were examined by varying methane and oxygen gas dissolution flow rates, 90 ml/min, 400 ml/min and 650 ml/min, in each. Simultaneously nitrification and denitrification was achieved. The total nitrogen removal rate was 15-mg N/g VSS. d, 21-mg N/g VSS. d and 26.4-mg N/g VSS. d at gas dissolution flow rate 90 ml/min, 400 ml/min and 650 ml/min, respectively. No significant accumulation of nitrite was found in this experiment. Nitrogen removal rates depend on gas dissolution flow rates. DO concentration was at 0.5-2 mg/L.
Nitrification inhibition due to aniline was investigated in completely mixed suspended-growth, batch, and continuous processes. Synthetic wastewater was used with aniline as the carbon source. The experiments were conducted at aniline concentrations inhibitory to nitrifier organisms. In the batch tests, degradation took place rapidly (within 4 to 6 hours) for initial aniline concentrations below 100 mg/L, with nitrification picking up as soon as the aniline concentration decreased to less than 3 to 4 mg/L. For initial aniline concentrations of 250 mg/L and higher, complete nitrification did not take place even though the aniline concentration decreased to less than 3 to 4 mg/L. This observation indicated nitrifier inhibition due to aniline. In the continuous experiments, a hydraulic residence time of 8 to 24 hours and a solids retention time of 8 to 24 days were maintained. Complete nitrification took place at bulk aniline concentrations less than 0.5 mg/L, while at higher aniline concentrations, nitrification inhibition took place. The inhibitory effect of aniline on the nitrification process was modeled using uncompetitive inhibition kinetics. Modeling of batch processes yielded the value for the inhibition constant for aniline, K i , as 3.3 mg/L. Modeling of continuous processes yielded criteria for stable process operation for nitrification under inhibitory conditions, which were also confirmed through experimental results. Water Environ. Res., 74, 531 ( 2002).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.