Research On Nitrification-Denitrification Coupling Performances Of Endogenous Nitrogen With Different Aeration Disturbance Depth And SOD Measurement Optimization

Since the exogenous pollution being controlled, the endogenous pollution becomes a major source of polluting the river system. The releasing problem of polluted sediment largely limits the remediation efficiency of malodorous river. Artificial aeration is a commonly used engineering measure in the riverway treatment, but the operation of aeration mode is still comparatively extensive. As a matter of fact, different aerators makes different disturbance effects even if keeping the same DO level. It influenced both the level of dissolved oxygen (DO) and the distribution of anoxic microzones directly, and then influcing the nitrification-denitrification processes of endogenous nitrogen. This thesis carried out a research of nitrification-denitrification coupling performance on different disturbance depths with malodorous river water and sediment, and studied the adsorption-desorption efficiency of sediment and flow filed inside the home-made river-simulated setup. In addition, this thesis optimizes the in situ measuring method by design an EMDVA SOD measuring device. Results showed that:The adsorption and desorption tests of the sediment present the scene of easy to desorb but hard to adsorb. Sediment adsorption of NH4+-N increases with the rising of the initial concentration, the thermodynamic adsorption phenomenon can be described by the Freundlich model. The dynamic adsorption process of sediment finished in30minutes while kinetics of adsorption process of sediment finished in5hour, and then stayed adsorption equilibrium. The secondary dynamics model is suitable for the two processes, the saturated adsorption quantity Qm is0.158mg-g-1, and the Qmax of desorption is0.514mg·g-1. The electromagnetic force SOD measuring device improved the circulation of overlying water, and avoids the stuck, rust problems which often occurs in common mechanical agitation devices. And it makes the overlying water circulation more sufficient, and much close to the real condition of water flow. By measuring the SOD of the5running with our device, the SOD of the stewing running is much lower than the other4aerating disturbance running by0.05184g·(m2·d)-1. The SOD of the4 aerating disturbance running are3.862,3.223,2.336and1.617g·(m2·d)-1,SOD decreases with the increasing of disturbance depth.Different aerating disturbances make the flow velocity and flow state variation in setup, the flow velocity stayed largest at the inflow profile and then decrease with the water flow in all4running. And by calculating the average Re of running1-4, we found that different aerating disturbance running showed different degrees of turbulent flow state, the order of disturbance intensity in each running is:running1> running2> running4> running3. On the sediment-water interface, running4appread the highest turbulence level, however running1showed the lowest turbulence degree.Aerating disturbance increased the reoxygenation rate of the overlying water, and the reoxygenation rate decreases with the increasing of disturbance depth. The reoxygenation rate of each running is0.07,0.59,0.56,0.41and0.10mg·(L·d)-1respectively. The aerated disturbances could facilitate the nitrification processes and the removal rate of NH4+-N are all above96.8%in each4running. And the removal rate of TN highest when the aerating disturbance is0.25m. The removal rate of NH4+-N, TN in the pore-water showed lower than the overlying water, the best condition is running1and3by16.2%and18.5%. Additionally, the reoxygenation rate and nitrification rate increased with the decrease of aerated depths. Running1showed the maximum nitrification rate by2.67mg·(L·d)-1, however running4showed the minimum nitrification rate by0.93mg·(L·d)-1. The denitrification rate of each aerated running is0.32.0.35、0.42and0.37mg·(L·d)-1. Denitrification rate decreases with the disturbing condition, running3showed the maximum denitrification rate by0.42mg·(L·d)-1, and running4showed the minimum denitrification rate by0.32mg·(L·d)-1. So we conclude that aerating disturbance of0.25m is the best condition for the coupling performance of nitrification-denitrification.