Study On The Condition Of Short-cut Nitrification-Denitrification And The Stability

As the nitrogen pollution in water bodies is becoming increasingly serious, and the nitrogen index becoming increasingly strict, short-cut biological nitrogen removal is regarded for its advantages, such as saving energy and carbon resource, shortening hydraulic residence time(HRT), reducing the amount of sludge-discharging, and etc.Based on the regulation of pH variation during organic oxidation, nitrifying and denitrifying in Sequencing Batch Reactor(SBR), combined with the change of Dissolved Oxygen(DO), this experiment controls the SBR in real time. This thesis is mainly on achieving short-cut nitrification-denitrification in low DO, high influent pH, and also discusses the stability of short-cut nitrification-denitrification. At the end of the thesis, the kinetic model of short-cut nitrification is proposed. The main conclusions are as follows:(1) In different influent ammonia nitrogen concentration, different influent pH value and different aeration rate, the regulation of pH is not affected, so it is feasible to judge the close of nitrification and denitrification, based on the characteristic points of pH curve.(2) Short-cut nitrification-denitrification sludge domestication is achieved successfully through lowing DO and increasing influent pH value on the basis of mature full nitrification-denitrification sludge. The accumulation rate of nitrite nitrogen can get above 95%. Then gradually increasing aeration rate, lowing influent pH, the short-cut nitrification is not destroyed in high DO, low pH conditions, the accumulation rate of nitrite nitrogen still maintained above 95%,sometimes can get 100%. This illuminates that domestication of certain bacterium is the key to short-cut nitrification. Once the nitrosomonas are mature and occupy absolute dominance, short-cut can stabilize for long time.(3) Overaeration can have short-cut nitrification change to full nitrification. On the fourth day after overaeration, the accumulation rate of nitrite nitrogen falls to 41.3% from 95%, the style of nitrification becomes full nitrification.(4) At the end, this thesis discusses the kinetic of short-cut nitrification, gets the kinetic model in the phase of short-cut nitrification, and calculated the kinetic parameters. Then validating the kinetic equation through comparing the experimental values to model values.