Alternating continuous flow aerobic granular sludge cultivation system

Abstract

The present invention provides an alternating continuous flow aerobic granular sludge cultivation system. The system includes a first alternating tank, a second alternating tank and an anoxic-oxic tank. The first alternating tank and the second alternating tank alternately serve as sedimentation tanks and reaction tanks, eliminating the need to set up a secondary sedimentation tank and improving the utilization rate of the structures. The first water distribution pipe and the second water distribution pipe distribute the influent to the bottom to contact the sludge preferentially, creating a high-load feast environment. The sludge in the first alternating tank and the second alternating tank alternately is in the feast and starvation states, promoting the formation of granular sludge. The first alternating tank and the second alternating tank intermittently are in anaerobic, aerobic and anoxic states, and the anoxic-oxic tank intermittently is in aerobic and anoxic states. The removal of pollutants in the sewage can be achieved without setting up a reflux device, avoiding the damage to the structure of granular sludge caused by power equipment. The first alternating tank and the second alternating tank alternately receive influent, and the anoxic-oxic tank alternately aerates and stirs, realizing the alternating operation of anaerobic, aerobic and anoxic states, and capable of improving the nitrogen and phosphorus removal performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and more specifically, relates to an alternating continuous flow aerobic granular sludge cultivation system. Background Art

[0002] Aerobic granular sludge is a granular microbial aggregate formed by the self-aggregation of microorganisms under special conditions, and has advantages that are difficult to match by the conventional activated sludge method: simultaneous nitrogen and phosphorus removal, dense structure, good sludge sedimentation performance, high biomass, strong shock resistance, etc. The aerobic granular sludge technology is considered to be a low-carbon and high-efficiency innovative technology in the sewage treatment industry due to its significant engineering advantages such as less land occupation, low energy consumption, and high efficiency, which meets the current technical requirements in the field of sewage treatment in China, can meet the requirements of upgrading and reducing consumption in the sewage treatment industry, helps to solve the problem of water environmental pollution, and is one of the sewage treatment technologies with the greatest development potential.

[0003] The aerobic granular sludge technology has been widely applied in the intermittent flow sewage treatment process, and there are engineering applications of intermittent flow aerobic granular sludge processes of different scales at home and abroad. In the continuous flow sewage treatment process, due to the use of the plug flow inlet mode, the substrate concentration gradient is small, the pollutant mass transfer driving force is small, which is not conducive to the cultivation and stable maintenance of aerobic granular sludge. In order to achieve the functions of nitrogen and phosphorus removal, it is necessary to set up anaerobic, anoxic and aerobic zones separately; at the same time, a secondary sedimentation tank is set up to realize the separation of the mixed liquor into mud and water; therefore, there are more structures in the traditional activated sludge process, and the utilization rate of the structures is low. The nitrification liquid reflux system and the sludge reflux system will also damage the structure of the sludge and affect the stability of the granular sludge. Summary of the Invention

[0004] The object of the present invention is to provide an alternating continuous flow aerobic granular sludge cultivation system to solve the problems of poor sedimentation performance, small particle size, easy fragmentation, poor nitrogen and phosphorus removal performance and low utilization rate of structures in the existing continuous flow activated sludge.

[0005] To achieve the above object, in a first aspect, the present invention provides an alternating continuous flow aerobic granular sludge cultivation system, comprising:

[0006] A first alternating tank, the first alternating tank is provided with a first water distribution unit, a first supernatant collection unit and a first aeration unit, the first water distribution unit is arranged at the top of the first alternating tank, a plurality of first water distribution pipes are connected below the first water distribution unit, the first water distribution pipes extend to the bottom of the first alternating tank, the first water distribution unit is further provided with a first raw water inlet and a first mixed liquor inlet, the first supernatant collection unit is provided with a first supernatant outlet, and the first alternating tank is further provided with a first sludge discharge port and a first mixed liquor outlet;

[0007] The second alternating tank is provided with a second water distribution unit, a second supernatant collection unit and a second aeration unit. A plurality of second water distribution pipes are connected below the second water distribution unit, and the second water distribution pipes extend to the bottom of the second alternating tank. The second water distribution unit is further provided with a second raw water inlet and a second mixed liquor inlet. The second supernatant collection unit is provided with a second supernatant outlet. The second alternating tank is further provided with a second sludge discharge port and a second mixed liquor outlet;

[0008] The anoxic tank is provided with a stirrer, a third aeration unit, a third raw water inlet, a third mixed liquor outlet, a fourth mixed liquor outlet, a third mixed liquor inlet and a fourth mixed liquor inlet. The third mixed liquor outlet is connected to the first mixed liquor inlet through a first mixed liquor valve. The fourth mixed liquor outlet is connected to the second mixed liquor inlet through a second mixed liquor valve. The third mixed liquor inlet is connected to the first mixed liquor outlet through a third mixed liquor valve. The fourth mixed liquor inlet is connected to the second mixed liquor outlet through a fourth mixed liquor valve.

[0009] Optionally, both the first water distribution unit and the second water distribution unit are water distribution weirs.

[0010] Optionally, both the first supernatant collection unit and the second supernatant collection unit are air weirs;

[0011] The first supernatant collection unit is further provided with a first air inlet and a first exhaust outlet. The first air inlet is provided with a first air inlet valve, and the first exhaust outlet is provided with a first exhaust valve;

[0012] The second supernatant collection unit is provided with a second air inlet and a second exhaust outlet. The second air inlet is provided with a second air inlet valve, and the second exhaust outlet is provided with a second exhaust valve.

[0013] Optionally, the alternating continuous flow aerobic granular sludge cultivation system further includes:

[0014] An air compressor, which is connected to the first air inlet valve and the second air inlet valve.

[0015] Optionally, the first supernatant outlet is provided with a first supernatant outlet valve;

[0016] The first sludge discharge port is provided with a first sludge discharge valve;

[0017] The second supernatant outlet is provided with a second supernatant outlet valve;

[0018] The second sludge discharge port is provided with a second sludge discharge valve.

[0019] Optionally, the alternating continuous flow aerobic granular sludge cultivation system further includes:

[0020] Original water tank, a water pump is provided in the original water tank, and the water pump is connected to the first raw water inlet, the second raw water inlet, and the third raw water inlet through a water supply pipeline. A first raw water inlet valve is provided at the first raw water inlet, a second raw water inlet valve is provided at the second raw water inlet, and a third raw water inlet valve is provided at the third raw water inlet.

[0021] Optionally, the first aeration unit, the second aeration unit, and the third aeration unit are all aeration discs. The first aeration unit is provided with a first aeration inlet, the second aeration unit is provided with a second aeration inlet, and the third aeration unit is provided with a third aeration inlet.

[0022] Optionally, the alternating continuous flow aerobic granular sludge cultivation system further includes:

[0023] A blower, the blower is connected to the first aeration inlet, the second aeration inlet, and the third aeration inlet. A first aeration valve is provided at the first aeration inlet, a second aeration valve is provided at the second aeration inlet, and a third aeration valve is provided at the third aeration inlet.

[0024] Optionally, the first aeration unit is arranged at the bottom of the first alternating tank;

[0025] The second aeration unit is arranged at the bottom of the second alternating tank;

[0026] The third aeration unit is arranged at the bottom of the anoxic-oxic tank.

[0027] Optionally, the alternating continuous flow aerobic granular sludge cultivation system further includes a control unit, and the control unit is electrically connected to the first mixed liquid valve, the second mixed liquid valve, the third mixed liquid valve, the fourth mixed liquid valve, the first air inlet valve, the first exhaust valve, the second air inlet valve, the second exhaust valve, the air compressor, the first supernatant water outlet valve, the first sludge discharge valve, the second supernatant water outlet valve, the second sludge discharge valve, the water pump, the first raw water inlet valve, the second raw water inlet valve, the third raw water inlet valve, the blower, the first aeration valve, the second aeration valve, the third aeration valve, and the stirrer.

[0028] In a second aspect, the present invention provides an alternating continuous flow aerobic granular sludge cultivation method, which uses the alternating continuous flow aerobic granular sludge cultivation system described in the first aspect, and includes the following steps:

[0029] Step 1: Introduce sewage into the first alternating tank and distribute it to the bottom, introduce the sewage at the top of the first alternating tank into the anoxic-oxic tank, introduce the mixed liquid in the anoxic-oxic tank into the second alternating tank, discharge the supernatant of the second alternating tank from the system, and continuously operate for a first set time;

[0030] Step 2: Aerate the first alternating pond and introduce the muddy water mixture into the facultative pond, then introduce the mixture in the facultative pond into the second alternating pond, and continuously operate for a second set time.

[0031] Step 3: Stop the water inlet of the first alternating pond and continue aeration, introduce the sewage into the facultative pond and stir it, then introduce the mixture in the facultative pond into the second alternating pond, and continuously operate for a third set time.

[0032] Step 4: Stop aeration of the first alternating pond and discharge the remaining sludge after sedimentation, stop stirring of the facultative pond and start aeration, then introduce the muddy water mixture in the facultative pond into the second alternating pond, and continuously operate for a fourth set time.

[0033] Step 5: Introduce the sewage into the second alternating pond and distribute it to the bottom, stop the water inlet of the facultative pond and continue aeration, introduce the mixture in the facultative pond into the first alternating pond, and discharge the supernatant of the first alternating pond from the system, and continuously operate for a fifth set time.

[0034] Step 6: Aerate the second alternating pond and introduce the muddy water mixture into the facultative pond, then introduce the mixture in the facultative pond into the first alternating pond, and continuously operate for a sixth set time.

[0035] Step 7: Stop the water inlet of the second alternating pond and continue aeration, introduce the sewage into the facultative pond and stir it, then introduce the mixture in the facultative pond into the first alternating pond, and continuously operate for a seventh set time.

[0036] Step 8: Stop aeration of the second alternating pond and discharge the remaining sludge after sedimentation, stop stirring of the facultative pond and start aeration, then introduce the muddy water mixture in the facultative pond into the first alternating pond, and continuously operate for an eighth set time.

[0037] Step 9: Repeat Steps 1 to 8 in a cycle.

[0038] The beneficial effects of the present invention are as follows: An alternating continuous flow aerobic granular sludge cultivation system is provided, including a first alternating tank, a second alternating tank, and an anoxic tank. The first alternating tank and the second alternating tank can alternately serve as a sedimentation tank and a reaction tank, eliminating the need for a separate secondary sedimentation tank and improving the utilization rate of the structures. The first water distribution pipe and the second water distribution pipe can distribute the raw water to the bottoms of the first alternating tank and the second alternating tank, enabling the influent to come into contact with the sludge first and creating a high-load feast environment. The sludge in the first alternating tank and the second alternating tank alternately experiences a feast and a starvation state, forming a feast-starvation alternating environment in terms of time and space, which helps secrete EPS and promotes the formation of granular sludge. The first alternating tank and the second alternating tank intermittently operate in anaerobic, aerobic, and anoxic states, and the anoxic tank intermittently operates in aerobic and anoxic states. Without setting up a sludge return system and a nitrification liquid return system, the removal of pollutants such as carbon, nitrogen, and phosphorus in the sewage can be achieved, reducing power equipment and energy consumption, and also avoiding the damage to the structure of granular sludge caused by power equipment such as return pumps. The first alternating tank and the second alternating tank alternately receive influent, and the anoxic tank alternately aerates and stirs, realizing the alternating operation of anaerobic, aerobic, and anoxic states, which can improve the nitrogen and phosphorus removal performance.

[0039] Other features and advantages of the present invention will be described in detail in the following specific implementation section. Brief Description of the Drawings

[0040] By describing the exemplary embodiments of the present invention in more detail in conjunction with the drawings, the above and other objects, features, and advantages of the present invention will become more apparent. Among them, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0041] Figure 1 Fig. shows a schematic structural diagram of an alternating continuous flow aerobic granular sludge cultivation system according to an embodiment of the present invention.

[0042] Figure 2 Fig. shows a flowchart of an alternating continuous flow aerobic granular sludge cultivation method according to an embodiment of the present invention.

[0043] Figure 3 Fig. shows a particle size distribution diagram of the sludge in the biological tank when the alternating continuous flow aerobic granular sludge cultivation system according to an embodiment of the present invention operates stably.

[0044] Description of the Reference Numerals in the Drawings:

[0045] 1. First alternating tank; 11. First water distribution unit; 111. First raw water inlet; 112. First raw water inlet valve; 113. First mixed liquor inlet; 114. First water distribution pipe; 12. First supernatant collection unit; 121. First supernatant outlet; 122. First supernatant outlet valve; 13. First aeration unit; 131. First aeration inlet; 132. First aeration valve; 141. First sludge discharge port; 142. First sludge discharge valve; 143. First mixed liquor outlet; 144. First air inlet; 145. First air inlet valve; 146. First exhaust port; 147. First exhaust valve;

[0046] 2. Second alternating tank; 21. Second water distribution unit; 211. Second raw water inlet; 212. Second raw water inlet valve; 213. Second mixed liquor inlet; 214. Second water distribution pipe; 22. Second supernatant collection unit; 221. Second supernatant outlet; 222. Second supernatant outlet valve; 23. Second aeration unit; 231. Second aeration inlet; 232. Second aeration valve; 241. Second sludge discharge port; 242. Second sludge discharge valve; 243. Second mixed liquor outlet; 244. Second air inlet; 245. Second air inlet valve; 246. Second exhaust port; 247. Second exhaust valve;

[0047] 3. Facultative oxygen tank; 31. Third aeration unit; 311. Third aeration inlet; 322. Third aeration valve; 32. Agitator; 331. Third raw water inlet; 332. Third raw water inlet valve; 333. Third mixed liquor outlet; 334. First mixed liquor valve; 335. Fourth mixed liquor outlet; 336. Second mixed liquor valve; 337. Third mixed liquor inlet; 338. Third mixed liquor valve; 339. Fourth mixed liquor inlet; 340. Fourth mixed liquor valve;

[0048] 4. Raw water tank; 41. Water pump; 42. Water supply pipeline;

[0049] 5. Air compressor;

[0050] 6. Blower;

[0051] 7. Control unit. Detailed implementation manners

[0052] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0053] As Figure 1As shown in the figure, this embodiment provides an alternating continuous flow aerobic granular sludge cultivation system, including:

[0054] The first alternating tank 1 is provided with a first water distribution unit 11, a first supernatant collection unit 12 and a first aeration unit 13. The first water distribution unit 11 is arranged at the top of the first alternating tank 1. Below the first water distribution unit 11, a plurality of first water distribution pipes 114 are connected. The first water distribution pipes 114 extend to the bottom of the first alternating tank 1. The first water distribution unit 11 is further provided with a first raw water inlet 111 and a first mixed liquid inlet 113. The first supernatant collection unit 12 is provided with a first supernatant outlet 121. The first alternating tank 1 is further provided with a first sludge discharge port 141 and a first mixed liquid outlet 143;

[0055] The second alternating tank 2 is provided with a second water distribution unit 21, a second supernatant collection unit 22 and a second aeration unit 23 inside. Below the second water distribution unit 21, a plurality of second water distribution pipes 214 are connected. The second water distribution pipes 214 extend to the bottom of the second alternating tank 2. The second water distribution unit 21 is further provided with a second raw water inlet 211 and a second mixed liquid inlet 213. The second supernatant collection unit 22 is provided with a second supernatant outlet 221. The second alternating tank 2 is further provided with a second sludge discharge port 241 and a second mixed liquid outlet 243;

[0056] The anoxic tank 3 is provided with a third aeration unit 31, a third raw water inlet 331, a third mixed liquid outlet 333, a fourth mixed liquid outlet 335, a third mixed liquid inlet 337 and a fourth mixed liquid inlet 339. The third mixed liquid outlet 333 is connected to the first mixed liquid inlet 113 through a first mixed liquid valve 334. The fourth mixed liquid outlet 335 is connected to the second mixed liquid inlet 213 through a second mixed liquid valve 336. The third mixed liquid inlet 337 is connected to the first mixed liquid outlet 143 through a third mixed liquid valve 338. The fourth mixed liquid inlet 339 is connected to the second mixed liquid outlet 243 through a fourth mixed liquid valve 340.

[0057] During specific implementation, as shown in Table 1, the cultivation of aerobic granular sludge using this system is divided into eight working procedures in a cycle.

[0058] Table 1

[0059]

[0060]

[0061] The specific working process of this system is as follows:

[0062] Procedure 1:

[0063] The first raw water inlet 111 is opened, the second raw water inlet 211 is closed, the third raw water inlet 331 is closed, the first supernatant outlet 121 is closed, the second supernatant outlet 221 is opened, the first aeration unit 13 is not working, the second aeration unit 23 is not working, the third aeration unit 31 is working, the first mixed liquor valve 334 is closed, the second mixed liquor valve 336 is opened, the third mixed liquor valve 338 is opened, the fourth mixed liquor valve 340 is closed, the agitator 32 is closed, the first sludge discharge port 141 is closed, and the second sludge discharge port 241 is closed.

[0064] The raw water enters the bottom of the first alternating tank 1 through the first water distribution unit 11 and contacts the sludge. The sludge at the bottom of the first alternating tank 1 is in a high-load feast environment, and denitrification reaction and phosphorus release by polyphosphate-accumulating organisms occur during this process. The supernatant in the first alternating tank 1 enters the anoxic tank 3 through the first mixed liquor outlet 143 and the third mixed liquor inlet 337. The third aeration unit 31 keeps the anoxic tank 3 in an aerated state and COD oxidation, nitrification reaction, and phosphorus uptake occur. The mixed liquor in the anoxic tank 3 enters the second alternating tank 2 through the fourth mixed liquor outlet 335 and the second mixed liquor inlet 213, and the mixed liquor undergoes gravity sedimentation in the second alternating tank 2 to achieve separation of mud and water. The supernatant in the second alternating tank 2 is collected by the second supernatant collection unit 22 and discharged from the system through the second supernatant outlet 221. The sludge in the second alternating tank 2 is in a starvation state. In this embodiment, the duration of this process is 60 min.

[0065] Process two:

[0066] The first raw water inlet 111 is opened, the second raw water inlet 211 is closed, the third raw water inlet 331 is closed, the first supernatant outlet 121 is closed, the second supernatant outlet 221 is opened, the first aeration unit 13 is working, the second aeration unit 23 is not working, the third aeration unit 31 is working, the first mixed liquor valve 334 is closed, the second mixed liquor valve 336 is opened, the third mixed liquor valve 338 is opened, the fourth mixed liquor valve 340 is closed, the agitator 32 is closed, the first sludge discharge port 141 is closed, and the second sludge discharge port 241 is closed.

[0067] Aeration starts in the first alternating tank 1, and COD oxidation, nitrification reaction, and phosphorus uptake occur; the mud-water mixture in the first alternating tank 1 continues to enter the anoxic tank 3 through the first mixed liquor outlet 143 and the third mixed liquor inlet 337 to supplement the sludge concentration in the anoxic tank 3. The anoxic tank 3 is in an aerated state for the removal of carbon, nitrogen, and phosphorus; the mixed liquor of the anoxic tank 3 enters the second alternating tank 2 through the fourth mixed liquor outlet 335 and the second mixed liquor inlet 213, and the second alternating tank 2 continues to precipitate and discharge water to complete the separation of mud and water. In this embodiment of this step, the duration of this process is 60 min.

[0068] Process three:

[0069] The first raw water inlet 111 is closed, the second raw water inlet 211 is closed, the third raw water inlet 331 is opened, the first supernatant outlet 121 is closed, the second supernatant outlet 221 is opened, the first aeration unit 13 is operating, the second aeration unit 23 is not operating, the third aeration unit 31 is not operating, the first mixed liquor valve 334 is closed, the second mixed liquor valve 336 is opened, the third mixed liquor valve 338 is closed, the fourth mixed liquor valve 340 is closed, the stirrer 32 is opened, the first sludge discharge port 141 is closed, and the second sludge discharge port 241 is closed.

[0070] The first alternating tank 1 stops water inlet and maintains the aeration state to complete the degradation of the remaining pollutants; the anoxic tank 3 starts water inlet and at the same time starts stirring to denitrify and remove the remaining nitrate nitrogen; the mixed liquor in the anoxic tank 3 enters the second alternating tank 2 through the fourth mixed liquor outlet 335 and the second mixed liquor inlet 213 to complete the separation of mud and water in the second alternating tank 2. In this embodiment, the duration of this process is 30 min.

[0071] Process Four:

[0072] The first raw water inlet 111 is closed, the second raw water inlet 211 is closed, the third raw water inlet 331 is opened, the first supernatant outlet 121 is closed, the second supernatant outlet 221 is opened, the first aeration unit 13 is not operating, the second aeration unit 23 is not operating, the third aeration unit 31 is operating, the first mixed liquor valve 334 is closed, the second mixed liquor valve 336 is opened, the third mixed liquor valve 338 is closed, the fourth mixed liquor valve 340 is closed, the stirrer 32 is closed, the first sludge discharge port 141 is opened, and the second sludge discharge port 241 is closed.

[0073] The first alternating tank 1 stops aeration and enters the sedimentation stage. The first sludge discharge port 141 is opened to discharge the remaining sludge in the first alternating tank 1; the anoxic tank 3 stops stirring and starts aeration; the mud-water mixture in the anoxic tank 3 enters the second alternating tank 2 to complete the separation of mud and water. In this embodiment, the duration of this process is 30 min.

[0074] Process Five:

[0075] The first raw water inlet 111 is closed, the second raw water inlet 211 is opened, the third raw water inlet 331 is closed, the first supernatant outlet 121 is opened, the second supernatant outlet 221 is closed, the first aeration unit 13 is not operating, the second aeration unit 23 is not operating, the third aeration unit 31 is operating, the first mixed liquor valve 334 is opened, the second mixed liquor valve 336 is closed, the third mixed liquor valve 338 is closed, the fourth mixed liquor valve 340 is opened, the stirrer 32 is closed, the first sludge discharge port 141 is closed, and the second sludge discharge port 241 is closed.

[0076] The raw water enters the bottom of the second alternating tank 2 through the second water distribution unit 21 and contacts the sludge at the bottom. The bottom sludge is in a high-load feast environment, and during this process, denitrification reaction and phosphorus release by polyphosphate-accumulating organisms occur. The supernatant at the top of the second alternating tank 2 enters the anoxic tank 3 through the second mixed liquid outlet 243 and the fourth mixed liquid inlet 339 and contacts the sludge in the anoxic tank 3. The water inlet to the anoxic tank 3 is stopped and aeration is maintained to complete the degradation of pollutants. The mixed liquid in the anoxic tank 3 enters the first alternating tank 1 through the third mixed liquid outlet 333 and the first mixed liquid inlet 113, and sedimentation occurs in the first alternating tank 1 to achieve separation of mud and water. The supernatant in the first alternating tank 1 is collected by the first supernatant collection unit 12 and discharged from the system through the first supernatant outlet 121. The sludge in the first alternating tank 1 is in a starving state. In this embodiment, the duration of this process is 60 min.

[0077] Process Step Six:

[0078] The first raw water inlet 111 is closed, the second raw water inlet 211 is opened, the third raw water inlet 331 is closed, the first supernatant outlet 121 is opened, the second supernatant outlet 221 is closed, the first aeration unit 13 is not working, the second aeration unit 23 is working, the third aeration unit 31 is working, the first mixed liquid valve 334 is opened, the second mixed liquid valve 336 is closed, the third mixed liquid valve 338 is closed, the fourth mixed liquid valve 340 is opened, the stirrer 32 is closed, the first sludge discharge port 141 is closed, and the second sludge discharge port 241 is closed.

[0079] Aeration is started in the second alternating tank 2, and the mud-water mixture in the second alternating tank 2 enters the anoxic tank 3 through the second mixed liquid outlet 243 and the fourth mixed liquid inlet 339. The anoxic tank 3 is in an aerated state. The mixed liquid in the anoxic tank 3 enters the first alternating tank 1 through the third mixed liquid outlet 333 and the first mixed liquid inlet 113 to complete separation of mud and water. The duration of this process is 60 min.

[0080] Process Step Seven:

[0081] The first raw water inlet 111 is closed, the second raw water inlet 211 is closed, the third raw water inlet 331 is opened, the first supernatant outlet 121 is opened, the second supernatant outlet 221 is closed, the first aeration unit 13 is not working, the second aeration unit 23 is working, the third aeration unit 31 is not working, the first mixed liquid valve 334 is opened, the second mixed liquid valve 336 is closed, the third mixed liquid valve 338 is closed, the fourth mixed liquid valve 340 is closed, the stirrer 32 is opened, the first sludge discharge port 141 is closed, and the second sludge discharge port 241 is closed.

[0082] The second alternating pond 2 stops water inflow and continues aeration to complete the degradation of the remaining pollutants; while the anoxic pond 3 starts water inflow, stirring is turned on to denitrify and remove the remaining nitrate nitrogen; the mixed liquid in the anoxic pond 3 enters the first alternating pond 1 to complete sedimentation separation. This stage lasts for 30 minutes.

[0083] Process Step VIII:

[0084] The first raw water inlet 111 is closed, the second raw water inlet 211 is closed, the third raw water inlet 331 is opened, the first supernatant outlet 121 is opened, the second supernatant outlet 221 is closed, the first aeration unit 13 is not working, the second aeration unit 23 is not working, the third aeration unit 31 is working, the first mixed liquid valve 334 is opened, the second mixed liquid valve 336 is closed, the third mixed liquid valve 338 is closed, the fourth mixed liquid valve 340 is closed, the stirrer 32 is closed, the first sludge discharge port 141 is closed, and the second sludge discharge port 241 is opened.

[0085] The second alternating pond 2 stops aeration and enters the sedimentation stage. The second sludge discharge port 241 is opened to discharge the remaining sludge; the anoxic pond 3 stops stirring and enters the aeration state. The mud-water mixture in the anoxic pond 3 enters the first alternating pond 1 to complete sedimentation separation. In this embodiment, the duration of this process is 30 minutes.

[0086] Specifically, by repeating the above process steps, aerobic granular sludge cultivation can be continuously carried out. Process Steps V - VIII repeat the working process of Process Steps I - IV, except that the water flow direction is switched from the first alternating pond 1 → anoxic pond 3 → second alternating pond 2 to the second alternating pond 2 → anoxic pond 3 → first alternating pond 1. The first water distribution pipe 114 and the second water distribution pipe 214 are used to distribute the raw water to the bottoms of the first alternating pond 1 and the second alternating pond 2, which can achieve the priority contact between the influent water and the sludge, creating a high-load feast environment for the bottom sludge. The sludge in the first alternating pond 1 and the second alternating pond 2 alternately undergoes feast and starvation states, forming a feast-starvation alternating environment in terms of time and space, which helps to secrete EPS and promote the formation of granular sludge. The first alternating pond 1 and the second alternating pond 2 are intermittently in anaerobic, aerobic, and anoxic states; the anoxic pond 3 is intermittently in aerobic and anoxic states; without setting up a sludge return and nitrification liquid return system, the removal of pollutants such as carbon, nitrogen, and phosphorus in the sewage can be effectively achieved, reducing power equipment and energy consumption; the sludge does not need to pass through sludge pumps and return pumps, avoiding the damage to the structure of granular sludge by power equipment such as return pumps. The first alternating pond 1 and the second alternating pond 2 alternately receive water, and the anoxic pond 3 alternately aerates and stirs, realizing the alternating operation of anaerobic, aerobic, and anoxic states, which helps to improve the nitrogen and phosphorus removal performance. The first alternating pond 1 and the second alternating pond 2 alternately serve as sedimentation ponds and reaction ponds, eliminating the need for a separate secondary sedimentation pond and improving the utilization rate of the structures.

[0087] In this embodiment, both the first water distribution unit 11 and the second water distribution unit 21 are water distribution weirs.

[0088] Specifically, the water distribution weir is a prior art, and its specific structure and working principle will not be elaborated.

[0089] Optionally, both the first supernatant collection unit 12 and the second supernatant collection unit 22 are air weirs;

[0090] The first supernatant collection unit 12 is further provided with a first air inlet 144 and a first air outlet 146. The first air inlet 144 is provided with a first air inlet valve 145, and the first air outlet 146 is provided with a first air outlet valve 147;

[0091] The second supernatant collection unit 22 is provided with a second air inlet 244 and a second air outlet 246. The second air inlet 244 is provided with a second air inlet valve 245, and the second air outlet 246 is provided with a second air outlet valve 247.

[0092] Specifically, the air weir is a prior art, including a cover plate and a water outlet weir. A sealed space is formed between the cover plate and the water outlet weir, and the water collection and interruption of water collection of the air weir are realized by changing the air pressure in the sealed space through exhaust and intake.

[0093] In this embodiment, the alternating continuous flow aerobic granular sludge cultivation system further includes:

[0094] An air compressor 5, and the air compressor 5 is connected to the first air inlet valve 145 and the second air inlet valve 245.

[0095] Specifically, the air pressure in the air weir is changed by the air compressor 5 to realize the water collection and interruption of water collection of the air weir.

[0096] Optionally, the first supernatant water outlet 121 is provided with a first supernatant water outlet valve 122;

[0097] The first sludge discharge port 141 is provided with a first sludge discharge valve 142;

[0098] The second supernatant water outlet 221 is provided with a second supernatant water outlet valve 222;

[0099] The second sludge discharge port 241 is provided with a second sludge discharge valve 242.

[0100] Specifically, the first supernatant water outlet valve 122 can realize the opening and closing of the first supernatant water outlet 121, the first sludge discharge valve 142 can realize the opening and closing of the first sludge discharge port 141, the second sludge discharge valve 242 can realize the opening and closing of the second sludge discharge port 241, and the second supernatant water outlet valve 222 can realize the opening and closing of the second supernatant water outlet 221.

[0101] In this embodiment, the alternating continuous flow aerobic granular sludge cultivation system further includes:

[0102] The original water tank 4 is provided with a water pump 41 inside. The water pump 41 is connected to the first raw water inlet 111, the second raw water inlet 211, and the third raw water inlet 331 through a water supply pipeline 42. The first raw water inlet 111 is provided with a first raw water inlet valve 112, the second raw water inlet 211 is provided with a second raw water inlet valve 212, and the third raw water inlet 331 is provided with a third raw water inlet valve 332.

[0103] Specifically, the original water tank 4 is used to store raw water, the water pump 41 is used to transport raw water to the first alternating tank 1, the second alternating tank 2, and the anoxic-oxic tank 3. The first raw water inlet valve 112 can open and close the first raw water inlet 111, the second raw water inlet valve 212 can open and close the second raw water inlet 211, and the third raw water inlet valve 332 can open and close the third raw water inlet 331.

[0104] In this embodiment, the first aeration unit 13, the second aeration unit 23, and the third aeration unit 31 are all aeration discs. The first aeration unit 13 is provided with a first aeration inlet 131, the second aeration unit 23 is provided with a second aeration inlet 231, and the third aeration unit 31 is provided with a third aeration inlet 311.

[0105] The first aeration unit 13 is arranged at the bottom of the first alternating tank 1;

[0106] The second aeration unit 23 is arranged at the bottom of the second alternating tank 2;

[0107] The third aeration unit 31 is arranged at the bottom of the anoxic-oxic tank 3.

[0108] Specifically, the aeration disc is a prior art and is arranged at the bottom of the container to disperse air into the water and provide sufficient oxygen for the microorganisms to degrade pollutants.

[0109] Optionally, the alternating continuous flow aerobic granular sludge cultivation system further includes:

[0110] A blower 6, the blower 6 is connected to the first aeration inlet 131, the second aeration inlet 231, and the third aeration inlet 311. The first aeration inlet 131 is provided with a first aeration valve 132, the second aeration inlet 231 is provided with a second aeration valve 232, and the third aeration inlet 311 is provided with a third aeration valve 322.

[0111] Optionally, the alternating continuous flow aerobic granular sludge cultivation system further includes a control unit 7, which is electrically connected to a first mixed liquor valve 334, a second mixed liquor valve 336, a third mixed liquor valve 338, a fourth mixed liquor valve 340, a first air inlet valve 145, a first exhaust valve 147, a second air inlet valve 245, a second exhaust valve 247, an air compressor 5, a first supernatant water outlet valve 122, a first sludge discharge valve 142, a second supernatant water outlet valve 222, a second sludge discharge valve 242, a water pump 41, a first raw water inlet valve 112, a second raw water inlet valve 212, a third raw water inlet valve 332, a blower 6, a first aeration valve 132, a second aeration valve 232, a third aeration valve 322 and a stirrer 32.

[0112] As Figure 2 shown, this embodiment also provides an alternating continuous flow aerobic granular sludge cultivation method, which uses the alternating continuous flow aerobic granular sludge cultivation system in this embodiment and includes the following steps:

[0113] Step 1: Introduce sewage into the first alternating tank 1 and distribute it to the bottom to contact with the sludge; introduce the sewage at the top of the first alternating tank 1 into the anoxic-oxic tank 3 for denitrification and phosphorus removal; introduce the mixed liquor in the anoxic-oxic tank 3 into the second alternating tank 2 for sedimentation; discharge the supernatant of the second alternating tank 2 from the system; continuously operate for 60 min;

[0114] Step 2: Aerate the first alternating tank 1 and introduce the mud-water mixture into the anoxic-oxic tank 3 for pollutant degradation; introduce the mixed liquor in the anoxic-oxic tank 3 into the second alternating tank 2 for sedimentation; continuously operate for 60 min;

[0115] Step 3: Stop the water inlet of the first alternating tank 1 and continue aeration to complete the degradation of the remaining pollutants; introduce sewage into the anoxic-oxic tank 3 and stir it to denitrify and remove the remaining nitrate nitrogen; introduce the mixed liquor in the anoxic-oxic tank 3 into the second alternating tank 2 for sedimentation, and continuously operate for 30 min;

[0116] Step 4: Stop aeration in the first alternating tank 1 for sedimentation and discharge the remaining sludge after sedimentation; stop stirring in the anoxic-oxic tank 3 and aerate it; introduce the mud-water mixture in the anoxic-oxic tank 3 into the second alternating tank 2 for sedimentation, and continuously operate for 30 min;

[0117] Step 5: Introduce sewage into the second alternating tank 2 and distribute it to the bottom to contact with the sludge; stop the water inlet of the anoxic-oxic tank 3 and continue aeration to complete the degradation of pollutants; introduce the mixed liquor in the anoxic-oxic tank 3 into the first alternating tank 1 and conduct sedimentation, and discharge the supernatant of the first alternating tank 1 from the system, and continuously operate for 30 min;

[0118] Step 6: The second alternating tank 2 is aerated and the mud-water mixture is introduced into the anoxic tank 3; the mixture in the anoxic tank 3 is introduced into the first alternating tank 1 for sedimentation, and the operation continues for 60 min;

[0119] Step 7: The second alternating tank 2 stops influent and continues aeration to complete the degradation of the remaining pollutants; the sewage is introduced into the anoxic tank 3 and stirred to denitrify and remove the remaining nitrate nitrogen; the mixture in the anoxic tank 3 is introduced into the first alternating tank 1 for sedimentation, and the operation continues for 60 min;

[0120] Step 8: The second alternating tank 2 stops aeration for sedimentation and discharges the remaining sludge after sedimentation; the anoxic tank 3 stops stirring and starts aeration; the mud-water mixture in the anoxic tank 3 is introduced into the first alternating tank 1 for sedimentation, and the operation continues for 30 min;

[0121] Step 9: Steps 1 to 8 are cyclically repeated.

[0122] Furthermore, in this embodiment, the raw water of the primary sedimentation tank of a certain water plant is treated by using this alternating continuous-flow aerobic granular sludge cultivation method. The water quality indexes of the raw water for COD, ammonia nitrogen, TN, and TP are 150 - 400 mg / L, 25 - 40 mg / L, 30 - 50 mg / L, and 3 - 5 mg / L respectively. By inoculating activated sludge and adopting an alternating operation mode, sludge granulation is achieved in 60 days, and the sludge particle size reaches 208.5 μm. The sludge particle size distribution in the biological tank during stable operation is as Figure 3 shown, and the effluent concentrations of COD, ammonia nitrogen, TN, and TP are: 18 - 30 mg / L, 0.3 - 1 mg / L, 12 - 18 mg / L, 0.1 - 0.5 mg / L.

[0123] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An alternating continuous flow aerobic granular sludge cultivation system, characterized in that, Comprising: A first alternating tank (1), the first alternating tank (1) is provided with a first water distribution unit (11), a first supernatant collection unit (12) and a first aeration unit (13), the first water distribution unit (11) is arranged at the top of the first alternating tank (1), a plurality of first water distribution pipes (114) are connected below the first water distribution unit (11), the first water distribution pipes (114) extend to the bottom of the first alternating tank (1), the first water distribution unit (11) is further provided with a first raw water inlet (111) and a first mixed liquid inlet (113), the first supernatant collection unit (12) is provided with a first supernatant outlet (121), the first alternating tank (1) is further provided with a first sludge discharge port (141) and a first mixed liquid outlet (143); A second alternating tank (2), the second alternating tank (2) is provided with a second water distribution unit (21), a second supernatant collection unit (22) and a second aeration unit (23), a plurality of second water distribution pipes (214) are connected below the second water distribution unit (21), the second water distribution pipes (214) extend to the bottom of the second alternating tank (2), the second water distribution unit (21) is further provided with a second raw water inlet (211) and a second mixed liquid inlet (213), the second supernatant collection unit (22) is provided with a second supernatant outlet (221), the second alternating tank (2) is further provided with a second sludge discharge port (241) and a second mixed liquid outlet (243); An anoxic tank (3), the anoxic tank (3) is provided with a stirrer (32), a third aeration unit (31), a third raw water inlet (331), a third mixed liquid outlet (333), a fourth mixed liquid outlet (335), a third mixed liquid inlet (337) and a fourth mixed liquid inlet (339), the third mixed liquid outlet (333) is connected to the first mixed liquid inlet (113) through a first mixed liquid valve (334), the fourth mixed liquid outlet (335) is connected to the second mixed liquid inlet (213) through a second mixed liquid valve (336), the third mixed liquid inlet (337) is connected to the first mixed liquid outlet (143) through a third mixed liquid valve (338), and the fourth mixed liquid inlet (339) is connected to the second mixed liquid outlet (243) through a fourth mixed liquid valve (340).

2. The alternating continuous flow aerobic granular sludge cultivation system according to claim 1, characterized in that Both the first water distribution unit (11) and the second water distribution unit (21) are water distribution weirs.

3. The alternating continuous flow aerobic granular sludge cultivation system according to claim 1, characterized in that Both the first supernatant collection unit (12) and the second supernatant collection unit (22) are air weirs; The first supernatant collection unit (12) is further provided with a first air inlet (144) and a first exhaust port (146), the first air inlet (144) is provided with a first air inlet valve (145), and the first exhaust port (146) is provided with a first exhaust valve (147); The second supernatant collection unit (22) is provided with a second air inlet (244) and a second air outlet (246). The second air inlet (244) is provided with a second air inlet valve (245), and the second air outlet (246) is provided with a second air outlet valve (247).

4. The alternating continuous flow aerobic granular sludge cultivation system according to claim 3, characterized in that It further includes: An air compressor (5), which is connected to the first air inlet valve (145) and the second air inlet valve (245).

5. The alternating continuous flow aerobic granular sludge cultivation system according to claim 4, wherein The first supernatant water outlet (121) is provided with a first supernatant water outlet valve (122); The first sludge discharge port (141) is provided with a first sludge discharge valve (142); The second supernatant water outlet (221) is provided with a second supernatant water outlet valve (222); The second sludge discharge port (241) is provided with a second sludge discharge valve (242).

6. The alternating continuous flow aerobic granular sludge cultivation system according to claim 5, wherein It further includes: A raw water tank (4), in which a water pump (41) is provided. The water pump (41) is connected to the first raw water inlet (111), the second raw water inlet (211) and the third raw water inlet (331) through a water supply pipeline (42). The first raw water inlet (111) is provided with a first raw water inlet valve (112), the second raw water inlet (211) is provided with a second raw water inlet valve (212), and the third raw water inlet (331) is provided with a third raw water inlet valve (332).

7. The alternating continuous flow aerobic granular sludge cultivation system according to claim 6, wherein The first aeration unit (13), the second aeration unit (23) and the third aeration unit (31) are all aeration discs. The first aeration unit (13) is provided with a first aeration inlet (131), the second aeration unit (23) is provided with a second aeration inlet (231), and the third aeration unit (31) is provided with a third aeration inlet (311).

8. The alternating continuous flow aerobic granular sludge cultivation system according to claim 7, characterized in that It further includes: A blower (6), which is connected to the first aeration inlet (131), the second aeration inlet (231) and the third aeration inlet (311). The first aeration inlet (131) is provided with a first aeration valve (132), the second aeration inlet (231) is provided with a second aeration valve (232), and the third aeration inlet (311) is provided with a third aeration valve (322).

9. The alternating continuous flow aerobic granular sludge cultivation system according to claim 8, wherein It further includes a control unit (7), which is electrically connected to the first mixed liquid valve (334), the second mixed liquid valve (336), the third mixed liquid valve (338), the fourth mixed liquid valve (340), the first air inlet valve (145), the first exhaust valve (147), the second air inlet valve (245), the second exhaust valve (247), the air compressor (5), the first supernatant water outlet valve (122), the first sludge discharge valve (142), the second supernatant water outlet valve (222), the second sludge discharge valve (242), the water pump (41), the first raw water inlet valve (112), the second raw water inlet valve (212), the third raw water inlet valve (332), the blower (6), the first aeration valve (132), the second aeration valve (232), the third aeration valve (322), and the stirrer (32).

10. An alternating continuous flow aerobic granular sludge cultivation method, which uses the alternating continuous flow aerobic granular sludge cultivation system described in any one of claims 1-9, characterized in that, It includes the following steps: Step 1: Introduce sewage into the first alternating tank (1) and distribute it to the bottom, introduce the sewage at the top of the first alternating tank (1) into the anoxic tank (3), introduce the mixed liquid in the anoxic tank (3) into the second alternating tank (2), discharge the supernatant of the second alternating tank (2) from the system, and continuously operate for a first set time; Step 2: Aerate the first alternating tank (1) and introduce the muddy water mixed liquid into the anoxic tank (3), introduce the mixed liquid in the anoxic tank (3) into the second alternating tank (2), and continuously operate for a second set time; Step 3: Stop the water inlet of the first alternating tank (1) and continue aerating, introduce sewage into the anoxic tank (3) and stir it, introduce the mixed liquid in the anoxic tank (3) into the second alternating tank (2), and continuously operate for a third set time; Step 4: Stop aerating the first alternating tank (1) and discharge the remaining sludge after precipitation, stop stirring the anoxic tank (3) and aerate it, introduce the muddy water mixed liquid in the anoxic tank (3) into the second alternating tank (2), and continuously operate for a fourth set time; Step 5: Introduce sewage into the second alternating tank (2) and distribute it to the bottom, stop the water inlet of the anoxic tank (3) and continue aerating, introduce the mixed liquid in the anoxic tank (3) into the first alternating tank (1), discharge the supernatant of the first alternating tank (1) from the system, and continuously operate for a fifth set time; Step 6: Aerate the second alternating tank (2) and introduce the muddy water mixed liquid into the anoxic tank (3), introduce the mixed liquid in the anoxic tank (3) into the first alternating tank (1), and continuously operate for a sixth set time; Step 7: Stop the water inlet of the second alternating tank (2) and continue aerating, introduce sewage into the anoxic tank (3) and stir it, introduce the mixed liquid in the anoxic tank (3) into the first alternating tank (1), and continuously operate for a seventh set time; Step 8: Stop aeration in the second alternating pond (2) and discharge the remaining sludge after sedimentation. Stop stirring in the anoxic pond (3) and start aeration. Introduce the muddy water mixture in the anoxic pond (3) into the first alternating pond (1), and continuously operate for the eighth set time; Step 9: Repeat steps 1 to 8 in a cycle.

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