The Research Of Short-Cut Nitrification And The Influencing Factor In A Sequencing Batch Reactor (SBR)

With the development of the industry and agriculture and the improvement of people's living standards in China, the nitrogenous organics in wastewater increased rapidly and the water environment is becoming worse and worse. The problem of eutrophication in water body has arisen extremely apparently. But the traditional treatment process of wastewater can not move the ammonia nitrogen effectively. Short-cut nitrification technology has been studied widely because of its advantages such as low coast, good effect and low energy consumption. But the achievement of the new nitrogen removal process is very difficult, and it is more difficult to maintain high nitrite accumulation rate during ambient conditions for a long time.To resolve these problems.A SBR process was adopted and returned sludge from wastewater treatment plant was cultivated in this study. Synthetic domestic wastewater was treated in the experiment. The short-cut nitrification system was started up successfully at low DO aeration rates. The influencing factors of the system were also studied.The start-up of this system has been achieved Under the conditions of temperature of 28±1℃, pH of 8.0,and low aeration rate.The stability of this system has been researched. The results indicate that the start-up could be completed rapid by varying aeration, but it can't made the system stable, The system could be stable under the fixed aeration time by discharging sludge and gradually increasing the NH4+-N concentration.In addition,the destination of nitration could be judged by combining the jump of the DO and pH value.The accumulation of NO2--N reached the greatest degree by controling the aeration time within 50 min after the nitrification was finished. The reason and the reversibility of the transformation from short-cut nitrification to nitrification have been researched, and found that the transformation process can not be changeover.There are many influencing factors of short-cut nitrification in the operation, such as temperature, DO, pH, C/N, sludge age and so on. The experiment studied and discussed these factors. The conclusions were obtained: Under the conditions of DO of 0.5⁰.7 mg/L , temperature is more than 23℃,the effectiveness of the short-cut nitrification is very good.The influence of different adding alkali mode is not very obvious.When the pH value between 7.7 and 8.5,the high pH value is more beneficial to the short-cut nitrification.Low C/N is more appropriate for the short-cut nitrification.The system could not be stable under the high C/N for long time.The effect of the short-cut nitrification is more better with the sludge ager for 10 d.The phenomenon of the TN losses has been researched. The results indicate that TN loss rate is rising with the increase of the aeration rate.The phenomenon of the TN losses was more obvious with the high C/N or long sludge age.The thesis studied the dynamics of shortcut nitrification, through least-squares procedure the thesis got the saturated constant of nitrosomas KN =3.07 mg/L, and the maximal oxidation rateÏ…max=0.08 h^-1, and the regression was relatively better.The research of DO concentration,C/N and different adding alkali mode have offered a data support for running cost.The research under the low temperature has offered a theoretical support for big temperature difference in the northern.And the research of SRT and dynamics have a important significance for the practical application.