Simultaneous Nitrification, Denitrification And Double Oxygenation Reactions Were Carried Out Using A Vertical Baffling Internal Circulation Biofilm Reactor

Benzoic acid(BA)and Phthalic acid(PA)are the intermediate products of bio-degradation of many aromatic compounds as refractory organic substances.Because Benzoic acid and its sodium salt can inhibit the activity of respiration enzymes in many microorganisms,it is widely used in industrial production,such as food bacteriostatic agent and dye-dyed mordant,which lead to Benzoic acid and sodium benzoate become common environmental pollutants.Similarly,phthalates are also a major pollutant in industrial waste water because they are often used for the production of Phthalic acid esters(PAEs).At the same time,as a common pollutant of domestic sewage and some industrial sewage,ammonia nitrogen and nitric acid are not only the important reason of serious eutrophication,but also the nitrite and nitrate produced by nitrification in the water,which causes serious harm to the animals in the water.Therefore,the effective treatment of Benzoic acid,Phthalic acid and ammonia nitrogen,accelerate its degradation in the sewage rate,in order to avoid harm to the ecological environment has important practical significance.At present,the most economical and effective method for the degradation of toxic and refractory materials BA and PA is aerobic bio-degradation,while the nitrification and denitrification reaction for ammonia-nitrogen treatment needs to be carried out in aerobic and anoxic environment respectively.At present,the treatment of these substances is isolated,and research is focused on the treatment of single pollutants,so it is difficult to remove these three kinds of pollutants in the same individual system.Therefore,it is a significant advance to treat refractory organics and ammonia-nitrogen simultaneously.In this experiment,the improved vertical direct current bio-film reactor was used to control dissolved oxygen to achieve both anoxic condition and aerobic condition in the same individual system,and to remove the waste water containing refractory organics and ammonia nitrogen simultaneously.In addition,the strategy of using different pollutant degradation sequences that is,according to the experimental research and reaction mechanism,di-oxygenation reaction of BA and PA cannot only provide carbon source for denitrification of nitrate or nitrite produced by ammonia nitrification,but also create the environment of hypoxia in the system,so therefractory organics should be added into the reactor after Nitrification is completed.So the bio-film reactor can optimize the treatment of these substances.The results are as follows:(1)The vertical baffled bio-reactor(VBBR)can be controlled by modified vertical flow inner loop bio-film reactor(2.0~4.0mg/L),and the oxygen-aerobic reaction and nitrification reaction as well as the anoxic denitrification reaction in the same reaction system are realized in the reactor.(2)Ammonia-nitrogen increases biological activity and promotes the reaction of di-oxygenation compared to the simultaneous reaction of BA and ammonia.Nitrate was not degraded and the reaction to di-oxygenation was inhibited when the continuous aerobic state in the reactor was adverse to denitrification.Under the condition of hypoxia,although the condition of denitrification reaction was satisfied successfully,the BA degradation was slowly.(3)In the initial test to add all target pollutants in addition to organic BA can be removed,ammonia nitrogen and nitric acid cannot be effectively removed.Then,through the determination of do change in the process of double oxygen reaction,it provides the data theory basis for the combination with denitrification reaction,and can make the reaction condition of the reactor in the condition of continuous hypoxia without manual adjustment.(4)By adjusting the strategy of combining di-oxygenation with the denitrification reaction,the condition that the nitrification reaction needs dissolved oxygen is satisfied,so that the 20mg/L ammonia nitrogen,the 100mg/L BA can be removed within 10 hours,and the calculation accords with N balance.(5)Optimal mixing times between the two-oxygen reaction and the nitrification-denitrification reaction were examined at time points of 0,3,and 5 hours to determine the most effective removal of all pollutants.It shows that 3h mixed processing effect is larger than 0h,and 5h mixed processing effect is the best time point,can be compared with 3h optimization.So that all pollutants are basically completely effective removal.