Process Design And Parameter Optimization Of Modified A~2/O Bottom Aeration Oxidation Ditch

In order to improve the removal rate of the traditional A²/O process in the sewage treatment,a modified A²/O process was adopted as the main research object.The sewage treatment progress was designed,and the operating parameters were optimized in this project.Compared with the tradition A²/O process,a pre-oxidation zone was added in front of the oxidation ditch in this modified A²/O process during the design.So the multipoint influent and multipoint reflux purposes can be achieved.The process can be adjusted conveniently according to the water quality.So the pollution factors of the future water can be removed accordingly.In addition,during the low load operation,the discontinuous operation mode can be adopted for blowing machine,which will decrease the electric power consumption greatly,and the cost of electric charge used for the sewage treatment per ton is lower than 0.3 Yuan.During the trial operation stage,it was found that the concentrations of NH₃-N and TN exceed the standard values,while the concentrations of other pollutants can meet the standard of the emissions.By investigating the relationship between the parameters such as dissolved oxygen and the active pollution concentration,etc.and removal rate of pollutants,it was found that the removal efficiency for these two pollutants is better when the dissolved oxygen concentration is controlled below 2mg·L^-1 and the active pollution concentration is controlled below 5.5⁶.0g·L^-1.By readjusting the parameters,the water quality was improved dramatically,and the emission of the all kinds of pollutants can meet the standard.Over 90%of the removal rate of NH₃-N can be achieved even the influent water quantity exceeds the design standard.The overall removal rate of Nitrogen is ca.70%,and the overall removal rate of Phosphorus is above 92%.These indicate that the modified A²/O process has a better efficiency on Nitrogen and Phosphorus removal,so this project provides the empirical data and practical processing technique for the sewage treatment plants using the similar technology.