Study On Nitrogen Removal Performance Of Rotary Anammox Bio-bed Reactor

Anaerobic ammonium oxidation(anamox)and its combined process are more efficient methods for removing nitrogen from water.Although anammox process was discovered in the last century,anammox has not been shipped to the engineering field on a large scale.The main reason is that the shortcomings of anammox growth and vulnerability to growth environment factors have not been effectively solved.These shortcomings have greatly limited the application of anammox process in the field of wastewater nitrogen removal.In view of the above shortcomings,the traditional anammox biofilm reactor was modified to rotate the biological bed in the reactor to increase the water flow velocity on the surface of the biofilm and improve the nitrogen removal performance of the reactor.This paper focuses on the nitrogen removal performance of the reactor during the start-up process and the changes in the surface of the biofilm.The Design Expert software was used to optimize the intermittent movement time of the reactor.The livestock wastewater discharged by semi-nitration running was introduced into the reactor,and the relevant exercise time was optimized and analyzed.The following conclusions were drawn:(1)The rotating biological bed reactor has the characteristics of fast film hanging speed during the start-up process and it is not easy to form a dead zone at the bottom of the reactor.After a long period of running,the surface of the biofilm is obviously granulated.Among them,the biofilm has a high protein content,which can reach about 300 mg/g-vss.Compared with the traditional internal circulation biofilm reactor,the rotating biobed reactor can effectively increase the water flow velocity on the surface of the biofilm in the reactor.The sequencing results showed that Candidatus Kuenenia was the main species in the biofilm,and its content was as high as 51.04%.(2)Sequencing experiments show that the total nitrogen removal rate is faster and faster with the rotation speed of the biological bed in the reactor.However,the faster rotation speed will cause damage to the surface of the biofilm.The optimum running time for total nitrogen removal is 51s-57 s i.e.the reactor stop time is 51 s and the running time is 57 s.The total nitrogen removal load of the reactor can reach 1837 mg/(L·d).Box-Behnken Design optimization experiment results shown that the reactor is operated at 45 s-30 s-42 s i.e.clockwise operation is 45 s,counterclockwise running time is 30s,and the stop time is 42s.The total nitrogen removal load of the reactor can reach 1932 mg/(L·d)under this operating condition.At low loads,the increase in water flow disturbances did not significantly affect the reactor removal load.(3)Under the influent load is 1400 mg/(L·d),the total nitrogen removal load of the reactor can reach 1018 mg/(L·d)when it is intermittently moved.Compared with the standing,the total nitrogen removal load of the reactor is increased by about 20%.In the case of an influent total nitrogen load of 1900 mg/(L·d),the total nitrogen removal load of the reactor for continuous rotational motion can reach about 1518 mg/(L·d).Compared with the standing,the total nitrogen removal load of the reactor is increased by about 25%.When the reactor is intermittently moved,the removal load can reach about 1439 mg/(L·d),and the reactor energy consumption can be reduced by about 50%.Under high load,the reactor is suitable for the positive-reverse-stop mode.Increasing the water flow helps to adapt the reactor to high load operation and improve reactor removal performance.(4)During the start-up operation of the semi-nitrification reactor,it has a good removal ability and can convert ammonia nitrogen in the water into NO2--N.After the mixed livestock waste water is passed into the semi-nitrification reactor,the livestock waste water will destroy the semi-nitrification process and make the nitrite bacteria inactive.After passing the semi-nitrified livestock waste water to the rotating biobed reactor,the removal load can reach 1150 mg/(L·d),and the removal rate is as high as 73%.The main reaction is anammox in the reactor.The optimal operating time of the total nitrogen removal load of the reactor is 44 s-56 s i.e.the operating time of the reactor is 44 s and the stopping time is 46 s.In this state,the total nitrogen removal load of the reactor can reach 1835 mg/(L·d).When the reactor performs forward-reverse-stop motion,the optimal total nitrogen running time is 65 s-31 s-85 s.Under this state,the total nitrogen removal load of the reactor can reach 1785 mg/(L·d).Compared with artificial wastewater,livestock wastewater increases the clockwise and stop time of the reactor.