Study On Denitrification And Phosphorus Removal In MIOD And Mechanism Of Separator

To seek for one measure to reinforce the removal efficiency of nitrogen and phosphorus, the inverse A2/O progress was applied in integrated oxidation ditch(IOD)to form a new wastewater system. The capacity of biological denitrification and phosphorus removal was studied in the experiment. The results show that in the condition of low carbon sources, the efficiency of denitrification and phophorus removal is fine and steady. When the water temperature is high in summer, the removal ratio of NH4+-N is no less than 85%, and the removal efficiency of TP can come at 70%. In the limits of experimental study, the optimal control parameters for the modified IOD model are that equals to 10d, the influent ratio of anoxic area equals to 0.8, and HRT of aerobic area equals to 12h. The separator is the core technology of the IOD, but some problems were exists in practical application, such as sedimentary sludge and float sludge. On the basis of prior study, several separator models were designed in the experiment. By observing and analyzing the phenomenon in the side channel model, influencing factors of the separation and the return of separator were determinated, and the principle on which were discussed and verified in the paper. Another important innovation of the experiment is that the hydraulic return can completely replace the mechanic return in the oxidation ditch model. The results show that the main reason of sedimenting and floating sludge are as following: 1) The return of separator is not smoothly; 2) Inclined-plates of separator module limit the free motion of sludge granules; 3) Inclined-plates of separator module adsorb sludge granules. In consideration of problems during the experiment, optimal model of side channel separator was designed. The characteristics of optimal module are as follows: 1) Canceling the upper inclined-plates of the module; 2) Installing water bars under the module; 3) Installing training plates at the back of side channel; 4) Installing steady flow devices at the forepart of side channel, such as water plates. The following experimental results show that the effect of the optimal model of side channel separator is fine and steady, the return of sludge is smoothly, and sendimenting and floating sludge are no more exist.