Anaerobic ammonia oxidation-couped denitrification composite denitrification system and quick starting method

[0029] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0030] The present invention proposes an anaerobic ammonium oxidation coupled denitrification compound denitrification system and a quick start-up method. The system mainly includes two parts: anoxic device and anaerobic device. The specific operation process is as follows:

[0031] The first step: set the initial hydraulic retention time and aeration time and interval, so as to determine according to the matrix composition (ammonium bicarbonate, potassium dihydrogen phosphate, sodium bicarbonate, anhydrous magnesium chloride, anhydrous calcium chloride, other trace elements) Nitrogen load;

[0032] Step 2: Determine the air flow of the aeration pump according to the set aeration interval and time, and use the gas flow meter to monitor in real time;

[0033] Step 3: Select the appropriate sludge (the end of the anoxic tank of the urban sewage plant) as the initial seed sludge, first use a longer hydraulic retention time (7h), wait for the reactor to run smoothly, and then according to the set hydraulic retention The time gradient gradually decreases the hydraulic retention time to achieve a higher nitrogen load. Combined with the amount of ammonia nitrogen and nitrite nitrogen in the effluent of the anoxic tank, adjust the aeration interval and aeration amount to determine the optimal dissolved oxygen amount, which is an anaerobic device. Form a good substrate condition to achieve anaerobic ammonium oxidation reaction as the main denitrification.

[0034] like image 3 Shown:

[0035] The first part: device composition;

[0036] This process is mainly composed of anoxic tank 1 and anaerobic tank 2. Anoxic tank 1 is periodically aerated by aeration pump 4 and adopts a sequence batch operation mode. Anaerobic tank 2 is an upflow sludge bed reactor ( UASB). Anoxic tank 1 mainly reacts as partial nitrification, and its effluent enters the anaerobic device for the next step of anaerobic ammonium oxidation and denitrification;

[0037] The second part: process parameters;

[0038] The parameters controlled by this process include hydraulic retention time (HRT), aeration time, aeration volume, etc.

[0039] Inoculate the seed sludge with denitrification as the main denitrification route and start the reactor with HRT of 7.0h. The amount of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in the effluent of anoxic tank 1 is measured every three days, and the aeration volume and aeration interval are adjusted in time according to the nitrosation efficiency, so as to achieve precise control of the dissolved oxygen in the system. Precise regulation of dissolved oxygen can ensure that the ratio of ammonia nitrogen to nitrite nitrogen in the anaerobic device is close to 1:1.32, creating a good reaction environment for anaerobic ammonia oxidation. In the start-up stage, since no external carbon source is added, denitrifying bacteria can only use the nitrate nitrogen produced by anaerobic ammonia oxidation and a small amount of organic matter produced by microbial metabolism and withering to denitrify, so the activity of denitrifying bacteria will not be too high to cause the system to denitrify. Mainly denitrification and denitrification.

[0040] During the start-up period, HRT was reduced from 7h to 4.0h (day 42), through precise regulation of aeration and dissolved oxygen, and through activity experiments to verify the start-up effect.

[0041] The reactor has been started and operated for 60 days, and the experimental results are attached figure 1 As shown, the total nitrogen removal rate maintained a gradual upward trend, and maintained at about 80% on the 54th to 60th day, achieving a good nitrogen removal effect. The reactor was started under the conditions of HRT 7h, aeration time 3min, aeration rate 0.06m3/h. Adjust the hydraulic retention time according to the amount of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen measured in the effluent and the removal rate of total nitrogen. When the total nitrogen removal rate reaches more than 60% and is stable for about 6 days, the hydraulic retention time can be reduced. On the 24th and 42nd day, the HRT was reduced to 5.5h and 4.0h, respectively. Adjust the aeration rate and aeration time according to the ratio of ammonia nitrogen and nitrite nitrogen in the effluent of the anoxic tank. When the ratio of ammonia nitrogen to nitrite nitrogen is greater than 1:1.32, it indicates that the conversion rate of ammonia nitrogen is insufficient, and the amount of dissolved oxygen in the system needs to be increased. Therefore, increasing the aeration rate will increase the dissolved oxygen in the system and increase the conversion rate of ammonia nitrogen. According to the results of each sample test, the aeration rate is constantly adjusted to keep the denitrification efficiency steadily rising.

[0042] The activities of anammox bacteria and denitrifying bacteria were measured before and after starting, and the results were as follows: figure 2 As shown, the activity of anammox bacteria during the start-up period was 4.32x10 before start-up -4 gN/gVSS/d increased to 0.254gN/gVSS/d, and the activity of denitrifying bacteria also increased significantly. However, due to the limitation of carbon source, this system is still a denitrification system based on Anammox and supplemented by denitrification.