Study On Denirtification Of Wastewater With Different C/N Ratio Treated By Circulating Exposure SBR Reactor

In recent years,with the continuous improvement of people's living standards and quality,the composition of the sewage is more and more complex.It is a common phenomenon that ammonia nitrogen is difficult to reach the standard after treatment.Especially after the high concentration organic wastewater is treated by the anaerobic process,the effluent quality shows the characteristics of less organic matter and low carbon nitrogen ratio,which makes the subsequent biological denitrification very difficult.In view of the problems encountered by the enterprise and the target wastewater,the laboratory research was carried out in this experiment.Combined with the characteristics of the effluent from the anaerobic treatment process,the subsequent denitrification treatment process matched with it was studied,and the control conditions were optimized to achieve the purpose of efficient denitrification.In this experiment,the fruit wastewater with different carbon nitrogen ratio prepared by hand is taken as the research object,and the time-controlled mechanical intermittent stirring aeration reactor(automatic intermittent water inlet sectional aeration system,patent No.: zl201510432180.5;laboratory use direct aeration equipment,patent No.: zl201510431817.9)is used as the experimental device.The device has been verified by the members of the research group.The conventional water treatment process has a good function of carbon and nitrogen removal.The main purpose of this study is to provide the living conditions for inhibiting nitrite oxidizing bacteria,promoting the denitrification of other denitrification mechanisms and realizing low-carbon denitrification.The dissolved oxygen concentration in the reaction system is determined by the rotation speed of the aeration device and the off aeration ratio.The effect of rotation speed and off aeration ratio on the effect of carbon and nitrogen removal is explored to find the best operation condition.The corresponding matrix degradation kinetic formula is established to verify the test results.The experiment lasted 122 days.(1)In the start-up stage,the reactor was inoculated with activated sludge for acclimation.The COD concentration increased from 627mg/L to 1170mg/L,and the influent volume increased from 10L/d to 20L/d,which took 22 days to complete sludge domestication.In this stage,the data show that the removal rate of COD and ammonia nitrogen is above 97%,and the effluent concentration is 25mg/L and3.8mg/L respectively,which can meet the discharge standard.A large number of bell worms were observed under the microscope,and the sludge activity and properties reached a good stable state,indicating that the experiment completed the start-up and domestication process.(2)After the acclimation,the proportion of ammonia nitrogen in wastewater should be increased.Under the conditions of carbon nitrogen ratio of 10 and 7(COD concentration of influent water is about 1100mg/L,ammonia nitrogen concentration of influent water is 108mg/L and 146mg/L respectively),the operation conditions should be changed to find out the control range suitable for this kind of wastewater.The experimental data show that the effluent concentration of COD,ammonia nitrogen and total nitrogen are respectively below 40mg/L,2.5mg/L and 11mg/L under the conditions of 450r/min rotation speed,15 minutes aeration time and 25 minutes sedimentation time,and the removal rate is kept at 97%,98% and 90%respectively,which shows that the reactor can effectively remove carbon and nitrogen.(3)When the influent volume increased from 20L/d to 40L/d,and the carbon nitrogen ratio was 11,6.5 and 4.5(COD concentration was about 1100mg/L,ammonia nitrogen concentration was 106mg/L,170mg/L and 240mg/L respectively),the off aeration ratio was fine adjusted to achieve good removal effect of total nitrogen.When the C/N ratio is 11,the best condition of the test is 450r/min,the cycle aeration stop time is set as 15 minutes of aeration and 25 minutes of standing;when the C/N ratio is 6.5 and 4.5 respectively,the best condition is 450r/min,the cycle aeration stop time is set as 20 minutes of aeration and 20 minutes of standing.(4)The experiment completed the research of removing carbon and nitrogen when the ratio of carbon to nitrogen was 11,6.5 and 4.5 respectively.Compared withthe conventional water treatment,under the condition of no carbon source,the COD,ammonia nitrogen and total nitrogen concentration of the treated effluent are all below the discharge standard by controlling the operation condition.According to the concentration change of each component in a cycle,it is proved that the short cut nitrification and denitrification occurs in the reaction process.(5)In the experimental stage of ammonia nitrogen concentration of 240mg/L,the experimental data was collated,the Monod equation was inferred,the kinetic parameters were solved by the graphical method,and the reactor was used to treat the pollution of nitrogenous fruit wastewater.The dynamic model of the object.The COD degradation kinetics model is(?);The kinetic model of ammonia nitrogen degradation is(?);The total nitrogen degradation kinetics model is(?).