Study On The Rapid Screen Method Of Aerobic Denitrification Bacteria And Treatment Of Denitrification In The Nitrate Wastewater

With the development of our economic, environmental pollution is more and more concerned by people. In the process of present economic development, water scarcity and water deterioration have become important limiting factors of national economic developments. The groundwater in many areas is polluted by nitrate more or less in our country. More content of nitrate in the waste water harm the people health very much, because nitrate will be deoxidized to nitrite by microorganism that gives rise to Methemoglobinemia and"Blue Baby"Syndrome. Besides, nitrate and nitrite will transform to nitrosamine and nitrosamidine under some conditions. So the remediation and precaution of the water pollution have been extremely urgent.At present, there are many kinds of nitrate removal technology which can be disparted two kinds: physical chemistry method and biology method. Compared with physical chemistry method, biology method has many characteristic such as low energy demand,high efficiency and no second pollution. Denitrification reaction always happens in anoxic and anaerobic condition, the heterophic bacteria can use NO2- and NO3- as the electron acceptor to turn the NH4+ into N2 to make nitrogen circulation proceed smoothly. Recently years,many internal and external reports confirmed that there are many microorganism processes that could not be seen in sewage treatment, such as aerobic denitrification, anaerobic ammonium oxidation,heterotrophic nitrification and so on, these nitrogen removal technology offer the new foundation for Aerobic denitrification. Compared with the eradiation denitrification in anoxic condition, Shortcut nitrification denitrification use the impersonality phenomena that the oxygen can not be supplied asymmetry, control the reaction dynamics balance to make the nitrification and denitrification reaction happen in the same time and space. While the traditional technique like A/O has the anoxic and anaerobic reaction section, then the nitrification and denitrification happens in different time. As the development of the technique, many scholars separated the aeration denitrification bacteria that can have the denitrification in anaerobic or aeration condition. Lone Frette, Shwu Ling Pai and Naoki Takaya used the aeration denitrification bacteria in practice and made the good effect. Though the study of Aerobic denitrification is in the starting, it will be one of the more important nitrogen removed technologies depend on the superiority.Mutation breeding will cause original bacteria lots of changes, some of them will have more effective in treating wastewater,others will not. Besides, they will be dead and have no ability of denitrification any more. If we select the bacteria at random, it would like looking for a needle in a haystack. So it is very important to select the better bacteria in a suitable and high efficiency way. To use the selective medium is the one of the methods.At first, we makes a special solid medium which can screen the aerobic denitrification bacteria according to the size of the blue color ring by using BTB as the indicator,and do research on the invalidation and stabilization of it. To screen the better aerobic denitrification bacteria which are from the sludge and mutation quickly by it is the key of the study. The result of experiment make know that the aerobic denitrification bacteria can easily make the green NO3--BTB solid medium change to blue, and the quality of the medium is better; in the dipping experiment, the coincidence rate of selection of the aerobic denitrification bacteria that are from sludge and mutation is 70% and 67%. But in semiquantitative analysis, we can know that it is not reliable if we only take the size of the color ring as the quantity of TN remove target, especially it is hard to achieve the certain linear relations, there are various reasons for consistent incompletely, such as the different of raising condition between solid and liquid, the different of time between viewing the blue ring and the best quantity of TN remove, so it is necessary to repeatedly screen by the quantity of TN remove in liquid medium. But according to the size of the blue ring in the first selection, we not only get more active and highly effective bacteria but also save the massive times that achieve the initial request. So the method of screening by the size of the blue ring is convenience and feasible.Upflow biological installment which has three series is used in the treatment of the nitrate sewage; the sewage enters the base of the pond and flows out above three times. At the same time, the wastewater through the global ceamsites filters in order to remove the nitrate. And to dispose of wastewater is with the technology of high speed raising microbiofilm by the mixing bacteria. After 5 days, the sign of microbilfilm is obvious, the effect of hang-up biofilm is better and the treating of nitrate sewage runs formally after two weeks. In the batch experiment, the best technology condition is studied by orthogonal experiment which indicates that the quantity of nitrate which is removed from the sewage are most when pH, temperature, C/N and the grow carbon is 7, 25℃, 5 and amber acid salt, respectively. In the successive experiment, the quantity of nitrate removes in each series is also determined as debugging the hydraulic residence time (HRT). The results of the research show that when HRT is 6～8h, the removal efficiency of nitrate is more than 90% as concerning about the efficiency of three series and the removal efficiency. Through the study of effect genes in the batch and successive denitrification experiment, and according to the interrelation and changing law discussed based on the results, we obtain the practical and reliable parameters that provide the new research direction for the method of removing the nitrate from the wastewater effectively and the technology of"simultaneous nitrification and denitrification"(SND).