Commissioning And Study Of Nitrogen Removal Effect Of SBR Process In Wastewater Treatment Plant

With the intensification of environmental pollution and water eutrophication, nitrogen removal technology, especially biological nitrogen removal technology for wastewater has caused extensive concern among countries all over the world. Now the shortage of carbon source during the denitrification process is the widespread problem for most WWTPs in China, especially for WWTPs in southern China. This problem has become an important factor which influencing the biological nitrogen removal efficiency. Therefore this project, which focused on the unsatisfactory TN removal effect in the No.1WWTP of Jinzhong city, was promoted to enhance the biological nitrogen removal effect and accomplish the efficient nitrogen removal effect.This study mainly explored the optimum operating conditions and operation parameters of biological nitrogen removal process. Ultimately, the TN of the effluent was capable of achieving the class A standard by adding carbon source. Not only it is reliable theoretical support for the SBR process commissioning and for the upgrade of the No.1WWTP of Jinzhong city, but also it is a useful reference for carbon adding in biological denitrification process for the sewage with low carbon and high nitrogen in China. All the experiments were conducted in No.1WWTP of Jinzhong city. Both the pilot SBR system and the full scale production SBR system were operated in synchronization.The first stage of the project is the experiments and the arrangements of the SBR sequence. The aim of this stage is try to reduce the TN of wastewater without adding carbon source. After the setting of preceding stirring for denitrification, setting of both the preceding stirring and the post stirring for denitrification and reducing the drainage ratio etc., the results indicated that the preceding stirring has good denitrification effect. The nitrate concentration dropped rapidly in less than30min during the stirring process which was right after the filling of raw water and the removal rate was86%-95%. However, the denitrification effect of post stirring was not obvious and in which the nitrate concentration only dropped2-4mg/L. After the reducing of drainage ratio from1/3to1/5, the nitrate removal effect during the preceding stirring was only55%-60%. Although the nitrate removal effect was improved after the adjustment of the operation condition, the effluent still could not stably meet the requirement.The second stage of the project is the tests of the effect of added glucose and raw sewage wastewater as carbon source on the denitrification process. Furthermore, the dosage of the glucose was optimized. The results indicated that if the dosage of the glucose was750mg/L, there would be a serious sludge bulking. The optimum dosage of the glucose was125mg/L meanwhile the TN removal rate was76.1%～83.8%and the TN of effluent was fixed between11～12mg/L therefore achieved the class A standard. This was about20%in average higher than the TN removal rate without adding of glucose. If adding1/5raw water during the during denitrification process instead of adding glucose, the nitrogen removal rate of the post stirring stage was improved to37.14%and the average TN of the effluent was15.8mg/L. Among these TN data, there were few if any of them could achieve the standard. But if adding2/5raw water, the nitrate removal rate of the post stirring stage was improved to52.94%. But the TN concentration of the effluent did not drop while the NH3-N concentration increased to6.7mg/L. Moreover, the TN concentration of the effluent increased to18.8mg/L rather than decreased and the effluent water quality deteriorated gradually.Another discovery was that adding glucose as external carbon source not only helped the removal of TN hence the TN of the effluent was lower than the standard, but also prompted the removal of the TP at the same time so the TP of the effluent could achieve the standard. It was supposed that adding glucose provided carbon source for both the denitrification and the phosphorus removal processes. For this reason, both the denitrification and the phosphorus removal processes could maintain high efficiency...