Anaerobic ammonia oxidation synchronous nitrogen and phosphorus removal treatment method

Abstract

The invention discloses an anaerobic ammonia oxidation synchronous nitrogen and phosphorus removal treatment method. Anaerobic ammonia oxidation synchronous nitrogen and phosphorus removal is completed by a system comprising an anaerobic tank, an aerobic tank, a sedimentation tank and an anaerobic ammonia oxidation tank. The four pool bodies are connected in sequence; the method comprises the following steps: inoculating respective required dominant bacteria in an anaerobic tank, an aerobic tank and an anaerobic ammonia oxidation tank, completing an anaerobic phosphorus release process under the action of phosphorus-accumulating bacteria when sewage enters the anaerobic tank, completing aerobic phosphorus uptake by using the phosphorus-accumulating bacteria in the aerobic tank, and converting ammonia nitrogen, organic nitrogen and ammonium ions into nitrite ions under the action of nitrosobacteria, sludge-water separation biological phosphorus removal is completed in the sedimentation tank, anaerobic ammonium oxidation bacteria in the anaerobic ammonium oxidation tank take HCO3 <-> as a carbon source to convert NH4 < + > and NO2 <-> into N2 in an anaerobic environment, anabolism of cells is completed, biological nitrogen removal is completed, and water is discharged from a water outlet pipe. The invention solves the technical problems of contradiction between denitrification and dephosphorization, low efficiency, difficulty in enrichment of anaerobic ammonium oxidation bacteria, long starting period and the like in the existing synchronous denitrification and dephosphorization technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental protection, particularly to the technical field of sewage treatment, and specifically relates to a treatment method for synchronous nitrogen and phosphorus removal by anaerobic ammonium oxidation. Background Art

[0002] At present, the principles of the synchronous nitrogen and phosphorus removal processes adopted for urban domestic sewage are basically the same. They all utilize the combination of biological nitrogen removal and biological phosphorus removal, and different microorganisms are used to achieve nitrogen and phosphorus removal under different oxygen-containing states.

[0003] Biological nitrogen removal generally includes three steps. In the first step, organic nitrogen is oxidized into ammonia under the action of ammonifying bacteria in an aerobic or anoxic environment. In the second step, ammonia and ammonium ions are oxidized into nitrite or nitrate by nitrifying bacteria in an aerobic environment. In the third step, nitrite and nitrate are reduced to nitrogen gas by denitrifying bacteria in an anoxic environment, and thus the nitrogen removal reaction is completed. This reaction process is relatively complex and there are mutual restrictions. Biological phosphorus removal relies on polyphosphate-accumulating organisms to release phosphorus in an anaerobic environment and absorb excessive phosphorus in an aerobic environment, and the purpose of phosphorus removal is achieved by discharging excess sludge. There are four types of strains involved in the entire synchronous nitrogen and phosphorus removal reaction process. Among them, nitrifying bacteria are the main strains affecting biological nitrogen removal effect. They are chemoautotrophic bacteria, with characteristics such as a relatively long generation time, a low growth rate, and being extremely sensitive to the environment.

[0004] The existing nitrogen and phosphorus removal processes are basically anaerobic + anoxic + aerobic + sedimentation. The activated sludge system is used more frequently. To maintain the sludge concentration in the system, sludge needs to be refluxed from the sedimentation tank to the anaerobic tank. In addition, due to the anoxic stage being placed in front, mixed liquor also needs to be refluxed from the end of the aerobic tank to the front section of the anoxic tank, that is, sludge reflux and mixed liquor reflux. The sludge returned from the sedimentation tank to the anaerobic tank contains all four types of strains for nitrogen and phosphorus removal at the same time. Polyphosphate-accumulating organisms are the main strains for biological phosphorus removal. Although they are heterotrophic bacteria, they have relatively strict requirements for organic matter and can only absorb volatile fatty acids (VFA) in the sewage. In the presence of other bacteria in the anaerobic tank, polyphosphate-accumulating organisms are at a growth disadvantage and cannot become the dominant strain in the anaerobic tank, which will inevitably affect the efficiency of biological phosphorus removal. In addition, inevitably, a part of nitrate is carried into the anaerobic tank by the refluxed sludge, seriously affecting the phosphorus release efficiency of polyphosphate-accumulating organisms and thus affecting the phosphorus removal efficiency.

[0005] The removal of phosphorus mainly depends on the discharge of excess sludge. The greater the discharge amount of excess sludge, the better the phosphorus removal effect. Phosphorus removal requires a relatively short sludge age, generally 3.5 - 7 days. Nitrifying bacteria have a relatively long generation time and require a relatively long sludge age, generally 10 - 22 days to grow and reproduce in large quantities and become the dominant strain in the aerobic tank to ensure the biological nitrogen removal effect. Therefore, the sludge age requirements for nitrifying bacteria and biological phosphorus removal are mutually contradictory.

[0006] The efficiency of biological nitrogen removal is positively correlated with the sum of the mixed liquor reflux ratio and the sludge reflux ratio. That is, the larger the sum of the two, the better the nitrogen removal effect. However, when the mixed liquor reflux ratio exceeds a certain value, the anoxic tank cannot maintain a good anoxic state, and the nitrogen removal effect will instead decline. Excessive return sludge volume will cause the anaerobic tank to be unable to maintain an anaerobic state, resulting in a decline in the biological phosphorus removal effect. Therefore, high nitrogen removal usually comes at the cost of sacrificing part of the phosphorus removal efficiency. Subsequently, chemical phosphorus removal units are added to make up for the phosphorus removal efficiency, increasing the system investment and operating costs.

[0007] To achieve the goal of high nitrogen removal efficiency using traditional simultaneous nitrogen and phosphorus removal processes, in addition to auxiliary chemical phosphorus removal, it is often necessary to set up a post-nitrogen removal unit and configure a carbon source dosing device, which are characterized by high oxygen demand and large carbon source dosing.

[0008] Anaerobic ammonium oxidation (ANAMMOX) technology is currently the most economical and effective biological nitrogen removal pathway known. Compared with traditional nitrification-denitrification technology, it has the advantages of low oxygen demand, low sludge production, and no need for external carbon source, and has broad prospects for popularization and application. However, ANAMMOX bacteria grow slowly, with a generation cycle of about 11 days, low cell yield, small volume, easy to lose, and extremely sensitive to environmental conditions, making it difficult to enrich ANAMMOX bacteria. The start-up time of ANAMMOX reactors is too long, severely restricting the development of ANAMMOX technology in the field of water treatment. Summary of the Invention

[0009] The present invention discloses an anaerobic ammonium oxidation simultaneous nitrogen and phosphorus removal treatment method in view of the deficiencies of the prior art. Aiming at the problems of the mutual contradiction between nitrogen and phosphorus removal and the difficulty in further improving the efficiency in the existing simultaneous nitrogen and phosphorus removal technology, as well as the difficulty in enriching bacteria and the long start-up period in the anaerobic ammonium oxidation process, the present invention provides an anaerobic ammonium oxidation simultaneous nitrogen and phosphorus removal treatment process method. The method of the present invention can simultaneously improve the efficiency of nitrogen and phosphorus removal, enhance the enrichment of ANAMMOX bacteria, shorten the start-up period, and reduce the operating cost.

[0010] The present invention is achieved through the following technical solutions:

[0011] An anaerobic ammonium oxidation simultaneous nitrogen and phosphorus removal method, characterized in that:

[0012] The simultaneous anaerobic ammonium oxidation for nitrogen and phosphorus removal is completed by a system consisting of an anaerobic tank, an aerobic tank, a sedimentation tank, and an anaerobic ammonium oxidation tank; the four tank bodies are sequentially connected in series, and are either co-wall tank bodies or independent tank bodies connected by pipelines; among them, the anaerobic tank is provided with a sludge return pipeline connected to the sedimentation tank; the bottom of the anaerobic ammonium oxidation tank receives the effluent from the sedimentation tank through a water distribution pipe; a heating coil is arranged in the water distribution area at the bottom of the anaerobic ammonium oxidation tank, the inlet of the heating coil is connected to the air inlet pipe, and the outlet is connected to an aeration device arranged at the bottom of the aerobic tank through a pipeline; the air inlet pipe is connected to a hot air device; an intercepting sieve plate is arranged at the upper part of the anaerobic ammonium oxidation tank to form a packing fixed bed from the bottom to the intercepting sieve plate and filled with suspended packing; an effluent channel is arranged on the circumferential wall above the intercepting sieve plate, and a water outlet pipe is arranged on the effluent channel to communicate with the subsequent treatment process; a stirrer is arranged at the center of the anaerobic ammonium oxidation tank; an effluent return pipe is arranged on the side wall at the bottom of the anaerobic ammonium oxidation tank;

[0013] The simultaneous anaerobic ammonium oxidation process for nitrogen and phosphorus removal includes the following steps:

[0014] First step, add the excess sludge from the sewage treatment plant for simultaneous nitrogen and phosphorus removal into the anaerobic tank and the aerobic tank, inoculate anaerobic ammonium oxidizing bacteria in the anaerobic ammonium oxidation tank, domesticate and cultivate the dominant bacteria in each tank body. The dominant bacteria in the anaerobic tank are phosphorus accumulating bacteria, the dominant bacteria in the aerobic tank are nitrite bacteria, and the dominant bacteria in the anaerobic ammonium oxidation tank are anaerobic ammonium oxidizing bacteria.

[0015] Second step, the sewage enters the anaerobic tank and is mixed with the reflux sludge from the sedimentation tank, and the anaerobic phosphorus release process is completed under the action of the phosphorus accumulating bacteria.

[0016] Third step, the sewage treated in the anaerobic tank flows by gravity to the aerobic tank. Control the pH in the aerobic tank to be 7.5 - 9.0 and the dissolved oxygen ≥ 2.0 mg / L. Use the phosphorus accumulating bacteria to complete aerobic phosphorus uptake, and at the same time convert ammonia nitrogen, organic nitrogen, and ammonium ions into nitrite ions under the action of nitrite bacteria.

[0017] Fourth step, the sewage passes through the connecting pipe between the aerobic tank and the sedimentation tank and enters the central vertical flow cylinder. The separation of mud and water is completed in the sedimentation tank. Phosphorus is discharged from the bottom sludge discharge pipe to leave the system, and at the same time, part of the sludge is refluxed to the anaerobic tank through a sludge pump to maintain the sludge concentration in the system; biological phosphorus removal is completed;

[0018] Compared with the traditional simultaneous nitrogen and phosphorus removal process, the phosphorus removal in this process is relatively independent. There are no nitrifying bacteria competing with the phosphorus removing bacteria in the anaerobic tank. Therefore, the phosphorus accumulating bacteria can become the dominant bacteria in the anaerobic tank, which can improve the efficiency of biological phosphorus removal and eliminate the subsequent chemical phosphorus removal process.

[0019] Fifth step, the sewage carrying ammonium ions and nitrite ions in the aerobic tank enters the anaerobic ammonium oxidation tank through the water distribution pipe at the lower end of the effluent channel at the top of the sedimentation tank, and is mixed evenly in the tank under the action of the stirrer. Control the pH in the tank to be 6.7 - 8.5 and the alkalinity to be greater than 4 times NH 4+ -N, COD / TKN is less than 3, and the water temperature is 20°C to 38°C; anaerobic ammonium-oxidizing bacteria in the pool use HCO 3 - as a carbon source to convert NH 4 + and NO 2 - into N 2 , completing the anabolic metabolism of cells; biological nitrogen removal is completed, and the water outlet pipe drains water.

[0020] Furthermore, a communication hole is provided in the partition between the bottom of the aerobic tank and the anaerobic tank, or water communication is achieved through a connecting pipe. An aeration device is provided at the bottom of the aerobic tank; the sedimentation tank and the aerobic tank are in water communication through a connecting pipe and a central vertical flow cylinder. A funnel-shaped sludge hopper is provided at the bottom of the sedimentation tank, and a sludge pump is arranged in the sludge hopper and connected to the anaerobic tank through a sludge return pipeline; a sedimentation tank outlet channel is provided on the upper annular wall of the sedimentation tank, and a water distribution pipe is provided at the bottom of the sedimentation tank outlet channel.

[0021] Furthermore, an ammonia nitrogen on-line detector is provided at the water inlet end of the aerobic tank; nitrite, nitrate, ammonia nitrogen on-line detectors and an alkalinity measuring instrument are provided in the sedimentation tank; dissolved oxygen, alkalinity, temperature, and PH detectors are provided in the anaerobic ammonium-oxidation tank.

[0022] Furthermore, the inlet of the connecting pipe provided between the sedimentation tank and the aerobic tank is located 700 mm below the water level line of the aerobic tank, and the outlet of the connecting pipe is communicated with the wall of the central vertical flow cylinder provided at the vertical center of the sedimentation tank.

[0023] Furthermore, the heating coil is a heating copper pipe and is arranged in a zigzag pattern.

[0024] Furthermore, the outlet of the water distribution pipe and the outlet of the water outlet return pipe are located in the water distribution area of the anaerobic ammonium-oxidation tank; the stirrer is provided with stirring blades at least in the water distribution area to achieve uniform water distribution or backwashing; the stirrer is a hyperbolic stirring device made of fiberglass reinforced plastic.

[0025] Furthermore, the packing fixed bed is composed of a packing interception sieve plate, a support structure and the pool body; the packing interception sieve plate is a stainless steel plate with uniformly opened holes, and the support structure is located below the packing interception sieve plate and is composed of angle steel or section steel; the packing interception sieve plate is a detachable structure; the filling rate of the fixed bed packing is 60-80% by volume.

[0026] Furthermore, both the sedimentation tank outlet channel and the outlet channel provided in the anaerobic ammonium-oxidation tank are triangular weir plate water collection systems.

[0027] Furthermore, the interception sieve plate is arranged 0.5 m below the outlet channel of the anaerobic ammonium-oxidation tank, and the opening rate of the interception sieve plate is 30-35% of the sieve plate area.

[0028] Furthermore, the anaerobic ammonium oxidation tank is backwashed once every two weeks. The backwash water is the effluent from the clear water tank, which enters the anaerobic ammonium oxidation tank through the effluent return pipe. The washing time is 10 - 15 minutes, and the washing intensity is 10 - 15 L / (m 2 .S).

[0029] Benefits compared with other simultaneous nitrogen and phosphorus removal systems:

[0030] (1) The anaerobic ammonium oxidizing bacteria used in the present invention are chemoautotrophic bacteria. Under anaerobic conditions, they use HCO 3 - as the carbon source. Therefore, when treating wastewater with a low carbon-nitrogen ratio, there is no need to additionally add a carbon source, saving the operating cost;

[0031] (2) The anaerobic ammonium oxidation tank of the present invention is arranged at the rear end of the aerobic tank. Nitrite and ammonium ions enter the anaerobic ammonium oxidation tank along with the effluent from the aerobic tank. Therefore, there is no need for an internal reflux system. The process flow is relatively simple, and the nitrogen removal efficiency is not affected by the internal reflux ratio and the anoxic state of the anoxic tank. At the same time, energy consumption is saved;

[0032] (3) The sedimentation tank at the front end of the present invention is only used for phosphorus removal, and the anaerobic ammonium oxidation tank at the rear end is dedicated to nitrogen removal. Separating the nitrogen removal sludge age and the phosphorus removal sludge age can improve the nitrogen removal and phosphorus removal efficiency simultaneously, saving the chemical phosphorus removal agent cost.

[0033] (4) The present invention makes full use of the characteristics that the generation time of anaerobic ammonium oxidation bacteria is long and the growth rate is lower than that of denitrifying bacteria. The sludge production is only 15% of that of the traditional biological nitrogen removal process, reducing the sludge treatment and disposal cost.

[0034] (5) Compared with the conventional biological nitrogen removal process, the nitrification reaction of the present invention only needs to proceed to the nitrite stage, so the residence time of the aerobic tank is relatively short. In addition, the nitrogen removal load of the anaerobic ammonium oxidation tank is higher than the heterotrophic denitrification load, and the volume is relatively small, and the residence time is short. Therefore, the residence time of the whole process is shorter than that of the conventional nitrogen and phosphorus removal process, saving the floor area and reducing the investment.

[0035] (6) The nitrification reaction of the aerobic tank in the present invention only needs to oxidize organic nitrogen and ammonia nitrogen to nitrite, and the oxygen demand is less than that of the conventional nitrogen removal process, saving energy consumption.

[0036] (7) The suspended packing added to the anaerobic ammonium oxidation tank of the present invention and the packing interception device at the top of the tank body form a fixed bed structure with a high filling rate, which has an interception effect on suspended solids. Therefore, there is no need to set up a mud-water separation device at the rear end, and the reaction process is short, saving the floor area.

[0037] (8) The present invention uses the effluent for backwashing and does not require a clear water tank. The backwash effluent is directly discharged into the subsequent treatment equipment without increasing the system burden.

[0038] (9) The present invention utilizes the heat carried by the air duct in the blower room to heat the copper pipes at the bottom of the anaerobic ammonium oxidation tank, maintaining the temperature of the anaerobic ammonium oxidation tank without the need to additionally increase heat and heat sources, thus saving energy consumption.

[0039] The present invention combines the biological phosphorus removal technology and the anaerobic ammonium oxidation denitrification technology, which can not only solve many contradictory problems in traditional biological denitrification and biological phosphorus removal, but also improve the denitrification and phosphorus removal effects simultaneously. The denitrification efficiency no longer depends on the mixed liquor and sludge return ratios, greatly saving energy consumption. The biological phosphorus removal system is completely independent and not affected by biological denitrification, with high phosphorus removal efficiency and no need for auxiliary chemical phosphorus removal, reducing the investment and operation costs. It also solves problems such as difficult enrichment of bacteria and long start-up period in the anaerobic ammonium oxidation process. Description of the Drawings

[0040] Figure 1 It is a schematic diagram of the anaerobic ammonium oxidation simultaneous denitrification and phosphorus removal treatment system of the present invention.

[0041] In the figure, 1 is the anaerobic tank, 2 is the aerobic tank, 3 is the sedimentation tank, 4 is the anaerobic ammonium oxidation tank, 6 is the sludge pump, 7 is the sludge return pipe, 8 is the aeration system, 9 is the effluent channel of the sedimentation tank, 10 is the water distribution pipe, 11 is the heating copper pipe, 12 is the water distribution area, 13 is the hyperbolic stirrer, 14 is the packing area, 15 is the suspended packing, 16 is the packing interception sieve plate, 18 is the support structure, 19 is the effluent collection area, 20 is the effluent channel, 21 is the triangular weir plate, 22 is the sludge hopper, 23 is the outlet pipe, 24 is the effluent return pipe, 25 is the air inlet pipe, 26 is the sludge discharge pipe, 27 is the ammonia nitrogen detector in the aerobic tank, 28 is the nitrate detector in the sedimentation tank, 29 is the nitrite detector in the sedimentation tank, 30 is the ammonia nitrogen detector in the sedimentation tank, 31 is the alkalinity detector in the sedimentation tank, 32 is the dissolved oxygen detector, 33 is the alkalinity detector, 34 is the thermometer, 35 is the pH meter, 36 is the central upflow cylinder, and 37 is the connecting pipe. Detailed Embodiments

[0042] The following further describes the present invention in combination with the detailed embodiments. The detailed embodiments are further explanations of the principles of the present invention and do not limit the present invention in any way. Technologies identical or similar to the present invention do not exceed the protection scope of the present invention.

[0043] Combined with the drawings, the anaerobic ammonium oxidation simultaneous denitrification and phosphorus removal technology of the embodiment of the present invention includes an anaerobic tank 1, an aerobic tank 2, a sedimentation tank 3, and an anaerobic ammonium oxidation tank 4. The four tank bodies are connected in sequence. Among them, the anaerobic tank 1, the aerobic tank 2, and the sedimentation tank 3 have the functions of biological phosphorus removal, carbonization, nitrification, and sedimentation separation, and are also the pretreatment of the anaerobic ammonium oxidation tank 4, providing nitrite and ammonium ions for the anaerobic ammonium oxidation tank 4. Among them, the anaerobic ammonium oxidation tank 4 adopts a fixed-bed structure.

[0044] The anaerobic tank 1 and the aerobic tank 2 adopt the activated sludge process.

[0045] A sludge return system is provided between the anaerobic tank 1 and the sedimentation tank 3, which consists of a sludge return pump 6 and a return pipeline 7.

[0046] An effluent weir 9 is provided at the top of the sedimentation tank 3, and a sludge hopper 22 is provided at the bottom; a central vertical flow cylinder 36 is provided in the middle and is connected to the anaerobic tank 1 through a connecting pipe 37 to achieve self-flow connection of water. A sludge discharge pipe 26 is also provided at the bottom of the sedimentation tank 3 to discharge sludge.

[0047] An aerobic tank ammonia nitrogen detector 27 is provided at the inlet end of the aerobic tank 2. A sedimentation tank nitrite detector 29, a sedimentation tank nitrate detector 28, a sedimentation tank ammonia nitrogen detector 30 and a sedimentation tank alkalinity measuring instrument 31 are provided in the sedimentation tank 3. A dissolved oxygen detector 32, an alkalinity detector 33, a thermometer 34 and a pH meter 35 are provided in the anaerobic ammonium oxidation tank.

[0048] The anaerobic ammonium oxidation tank 4 includes, from bottom to top: heating copper pipes 11, a water distribution area 12, a hyperbolic stirrer 13, a packing area 14, a packing interception device 16, and an effluent collection area 19.

[0049] The heating copper pipes 11 provided in the bottom area of the anaerobic ammonium oxidation tank 4 are used for heat preservation of the anaerobic ammonium oxidation tank. After the heated air generated by the blower room enters through the air inlet pipe 25, it first passes through the heating copper pipes 11 provided in the bottom area of the anaerobic ammonium oxidation tank 4, and then enters the aerobic tank 2 for aeration through the aeration system 8. The heating copper pipes 11 are arranged in a zigzag shape.

[0050] The water distribution area 12 of the anaerobic ammonium oxidation tank 4 is provided with a water distribution pipe 10 and an effluent return pipe 24. During normal operation, the influent is evenly distributed in the tank under the action of the hyperbolic stirrer, and during backwashing, the influent and the washing influent are evenly backwashed under the agitation of the hyperbolic stirrer.

[0051] The hyperbolic stirrer 13 in the anaerobic ammonium oxidation tank is made of fiberglass reinforced plastic. The guide rod of the hyperbolic stirrer 13 passes through the packing interception sieve plate 16 and is connected to the impeller. During maintenance, 4 movable packing interception sieve plates 16 around the guide rod are removed.

[0052] Suspended packing 15 is filled in the anaerobic ammonium oxidation tank 4 to form a fixed bed structure, which provides an attachment point for anaerobic ammonium oxidizing bacteria. The anaerobic ammonium oxidizing bacteria can grow and reproduce on the surface of the suspended packing 15 and form a stable biofilm structure, which is beneficial to the growth of anaerobic ammonium oxidizing bacteria and enhances the enrichment of anaerobic ammonium oxidizing bacteria at the same time. The fixed bed structure is formed by the suspended packing 15 with a filling rate of 60-80% and the packing interception device, which can reduce the damage of hydraulic shear force to the sludge aggregates and has a retention effect. The suspended packing 15 is made of HDPE material, and the specific surface area is 400-600m 2 / m 3 .

[0053] The packing fixed-bed device consists of a packing interception sieve plate 16 and a support structure 18. The packing interception sieve plate 16 is made of stainless steel and consists of several stainless steel plates with uniform openings and the same size. The support structure 18 is located below the baffle and consists of angle steel and section steel. The packing interception sieve plate 16 is movable. The packing interception sieve plate 16 is about 0.5 m below the water outlet channel, and the porosity is 30 - 35%.

[0054] At a certain height below the top of the anaerobic ammonium oxidation tank 4, a water outlet collection system composed of a water outlet channel 20 and a triangular weir plate 21 is provided on the surrounding walls. After the water outlet of the anaerobic ammonium oxidation tank 4 is collected, it enters the next-stage treatment structure through a water outlet pipe 23.

[0055] For the operation of the anaerobic tank 1, aerobic tank 2, and sedimentation tank 3, the nitrification reaction process in the aerobic tank needs to be controlled.

[0056] The water quality in the aerobic tank 2 should meet the following standards: pH is 7.5 - 9.0; dissolved oxygen (DO) is 0.2 - 1.0 mg / L, which can be adjusted according to the requirements of the water outlet quality.

[0057] The influent water quality of the anaerobic ammonium oxidation tank 4 should meet the following standards: pH is 6.7 - 8.5; the alkalinity should be greater than 4 times NH 4 + -N. When not meeting the requirement, alkali or acid supplement agents should be added; COD / TKN is less than 3; the water temperature of the anaerobic ammonium oxidation tank is preferably 20°C - 38°C.

[0058] The backwashing water of the anaerobic ammonium oxidation tank 4 is the effluent from the clear water tank. The backwashing frequency is once every two weeks, the backwashing time is 10 - 15 min, and the backwashing intensity is 10 - 15 L / (m 2 .S).

[0059] The backwashing water of the anaerobic ammonium oxidation tank 4 is connected to the subsequent treatment equipment.

[0060] The process flow of the anaerobic ammonium oxidation synchronous nitrogen and phosphorus removal treatment in the present invention is as follows:

[0061] First step: Add the surplus sludge from the synchronous nitrogen and phosphorus removal sewage treatment plant into the anaerobic tank 1 and aerobic tank 2, and inoculate anaerobic ammonium oxidation bacteria into the anaerobic ammonium oxidation tank 4 to domesticate and cultivate the dominant strains in each tank. The dominant strain in the anaerobic tank 1 is polyphosphate-accumulating organisms, the dominant strain in the aerobic tank 2 is nitrite bacteria, and the dominant strain in the anaerobic ammonium oxidation tank 4 is anaerobic ammonium oxidation bacteria.

[0062] Second step: Sewage enters the anaerobic tank 1 and is mixed evenly with the reflux sludge from the sedimentation tank 3, and the anaerobic phosphorus release process is completed under the action of polyphosphate-accumulating organisms.

[0063] In the third step, the sewage from anaerobic pool 1 flows by gravity to aerobic pool 2, and the pH in the aerobic pool is controlled at 7.5-9.0 and the dissolved oxygen is controlled at 0.2-1.0 mg / L. Polyphosphate bacteria are used to complete aerobic phosphorus absorption. At the same time, ammonia nitrogen, organic nitrogen and ammonium ions are converted into nitrite ions under the action of nitrite bacteria.

[0064] Step 4: The sewage enters the central vertical flow tube 36 through the connecting pipe 37 between the aerobic tank 2 and the sedimentation tank 3, and the mud and water separation is completed in the sedimentation tank. Phosphorus leaves the system with the discharged residual sludge. At the same time, part of the sludge is returned to the anaerobic tank through the sludge pump to maintain the sludge concentration of the system. At this point, biological phosphorus removal is completed.

[0065] The phosphorus removal process of the present invention is relatively independent, and there are no nitrifying bacteria in the anaerobic tank that compete with the phosphorus removal bacteria. Therefore, polyphosphate bacteria can become the dominant bacteria in the anaerobic tank, which can improve the efficiency of biological phosphorus removal and save the subsequent chemical phosphorus removal process.

[0066] Step 5: The sewage carrying ammonium ions and nitrite ions in the aerobic pool enters the anaerobic ammonia oxidation pool 4 through the water distribution pipe 10 at the lower end of the outlet channel at the top of the sedimentation pool, and is mixed evenly in the pool under the action of the hyperbolic stirrer 13, and the pH in the pool is controlled to be 6.7-8.5 and the alkalinity is greater than 4 times NH 4 + -N, COD / TKN is less than 3, and the water temperature is 20℃~38℃.

[0067] Using anaerobic ammonia-oxidizing bacteria in the pool to oxidize HCO 3 - NH 4 + and NO 2 - , converted into N 2 , and complete the anabolism of the cells, thus completing the biological denitrification.

[0068] In the process of the present invention, phosphorus removal is performed first and nitrogen removal is performed later. On the one hand, nitrite and ammonium ions enter the anaerobic ammonia oxidation tank with the effluent from the aerobic tank, and an internal recirculation system is not required. The process flow is relatively simple, and the nitrogen removal efficiency is not affected by the internal recirculation ratio and the anoxic state of the anoxic tank. On the other hand, the denitrification sludge age and the phosphorus removal sludge age are separated, which can simultaneously improve the efficiency of nitrogen removal and phosphorus removal.

[0069] The process of the present invention has the advantages of short residence time, small floor area, and low investment. On the one hand, the nitrification reaction of the present invention only needs to proceed to the nitrite stage. Therefore, the residence time of the aerobic tank is relatively short. On the other hand, the nitrogen removal load of the anaerobic ammonium oxidation tank is higher than that of heterotrophic denitrification, so the volume of the anaerobic ammonium oxidation tank is relatively small and the residence time is short. The nitrification reaction in the aerobic tank only needs to oxidize organic nitrogen and ammonia nitrogen into nitrite, and the oxygen consumption is less than that of the conventional nitrogen removal process. Moreover, the anaerobic ammonium oxidation tank needs to maintain an anaerobic state, so the whole process also has the advantage of low energy consumption.

[0070] Anaerobic ammonium oxidizing bacteria are chemolithoautotrophic bacteria that use HCO 3 - as a carbon source. Therefore, when treating wastewater with a low carbon-nitrogen ratio, there is no need to additionally add a carbon source, saving the operation cost. In addition, the generation time of anaerobic ammonium oxidizing bacteria is long and the growth rate is lower than that of denitrifying bacteria. Therefore, the sludge yield is only 15% of that of the traditional biological nitrogen removal process, reducing the sludge treatment and disposal cost.

Claims

1. A method for simultaneous anaerobic ammonium oxidation denitrification and phosphorus removal, characterized in that: The simultaneous nitrogen and phosphorus removal by anaerobic ammonia oxidation is completed by a system consisting of an anaerobic tank, an aerobic tank, a sedimentation tank and an anaerobic ammonia oxidation tank; the four tank bodies are linked in sequence, and are common-wall tank bodies or independent tank bodies connected by pipelines; among them, the anaerobic tank is provided with a sludge return pipeline connected to the sedimentation tank; the bottom of the anaerobic ammonia oxidation tank receives the effluent from the sedimentation tank through a water distribution pipe; a heating coil is provided in the water distribution area at the bottom of the anaerobic ammonia oxidation tank, the inlet of the heating coil is connected to the air inlet pipe, and the outlet is connected to the aeration device provided at the bottom of the aerobic tank through a pipeline; the air inlet pipe is connected to the hot air device; an interception sieve plate is provided on the upper part of the anaerobic ammonia oxidation tank to form a fixed bed of filler from the bottom to the interception sieve plate and fill it with suspended filler; an outlet channel is provided on the annular wall above the interception sieve plate, and an outlet pipe is provided on the outlet channel to connect with the subsequent treatment process; an agitator is provided in the center of the anaerobic ammonia oxidation tank; an outlet reflux pipe is provided on the bottom side wall of the anaerobic ammonia oxidation tank; The anaerobic ammonium oxidation simultaneous nitrogen and phosphorus removal process includes the following steps: The first step is to add the wastewater treatment plant surplus sludge with simultaneous nitrogen and phosphorus removal into the anaerobic tank and the aerobic tank, inoculate anaerobic ammonia oxidizing bacteria into the anaerobic ammonia oxidation tank, and acclimate and cultivate the dominant bacteria in each tank; the dominant bacteria in the anaerobic tank are polyphosphate bacteria, the dominant bacteria in the aerobic tank are nitrite bacteria, and the dominant bacteria in the anaerobic ammonia oxidation tank are anaerobic ammonia oxidizing bacteria; In the second step, the sewage enters the anaerobic tank and mixes with the return sludge from the sedimentation tank to complete the anaerobic phosphorus release process under the action of polyphosphate bacteria; Step 3: After the anaerobic tank treatment, the sewage flows by gravity to the aerobic tank, and the pH in the aerobic tank is controlled to be 7.5-9.0 and the dissolved oxygen ≥2.0 mg / L. Polyphosphate bacteria are used to complete aerobic phosphorus absorption, and at the same time, ammonia nitrogen, organic nitrogen and ammonium ions are converted into nitrite ions under the action of nitrite bacteria; Step 4: The sewage enters the central vertical flow tube through the connecting pipe between the aerobic tank and the sedimentation tank, and the mud and water are separated in the sedimentation tank. Phosphorus is discharged from the system through the bottom mud discharge pipe. At the same time, part of the sludge is returned to the anaerobic tank through the sludge pump to maintain the sludge concentration of the system. Biological phosphorus removal is completed; Step 5: The sewage carrying ammonium ions and nitrite ions in the aerobic pool enters the anaerobic ammonia oxidation pool through the water distribution pipe at the lower end of the outlet channel at the top of the sedimentation tank. Under the action of the agitator, it is evenly mixed in the pool to control the pool pH to 6.7-8.5 and the alkalinity to be greater than 4 times NH4 + -N, COD / TKN less than 3, water temperature 20℃~38℃; anaerobic ammonia oxidizing bacteria in the pool convert HCO3 - NH4 + and NO2 - Converted into N2, completing the anabolism of cells; biological denitrification is completed and water is discharged into the outlet pipe.

2. The anaerobic ammonium oxidation simultaneous denitrification and phosphorus removal method according to claim 1, characterized in that: A connecting hole is arranged on the partition plate between the bottom of the aerobic tank and the anaerobic tank, or water is connected through a connecting pipe, and an aeration device is arranged at the bottom of the aerobic tank; The sedimentation tank and the aerobic tank are connected by water through a connecting pipe and a central vertical flow tube. A funnel-shaped sludge hopper is arranged at the bottom of the sedimentation tank. A sludge pump is arranged in the sludge hopper and connected to the anaerobic tank through a sludge return pipe. A sedimentation tank outlet channel is arranged on the upper ring wall of the sedimentation tank, and a water distribution pipe is arranged at the bottom of the sedimentation tank outlet channel.

3. The anaerobic ammonium oxidation simultaneous denitrification and phosphorus removal method according to claim 2, characterized in that: The aerobic pool is provided with an online ammonia nitrogen detector at the water inlet; the sedimentation tank is provided with online nitrite, nitrate, ammonia nitrogen detectors and an alkalinity meter; the anaerobic ammonia oxidation tank is provided with dissolved oxygen, alkalinity, temperature, and pH detectors.

4. The anaerobic ammonium oxidation simultaneous denitrification and phosphorus removal method according to claim 2, characterized in that: The inlet of the connecting pipe arranged between the sedimentation tank and the aerobic tank is located 700mm below the water level of the aerobic tank, and the outlet of the connecting pipe is connected to the central vertical flow cylinder wall arranged at the vertical center of the sedimentation tank.

5. The method for simultaneous anaerobic ammonium oxidation denitrification and phosphorus removal according to claim 2, characterized in that: The heating coil is a heating copper tube, which is arranged in a U-shaped pattern.

6. The method for simultaneous anaerobic ammonium oxidation denitrification and phosphorus removal according to claim 2, characterized in that: The outlet of the water distribution pipe and the outlet of the water return pipe are located in the water distribution area of ​​the anaerobic ammonia oxidation tank; the agitator is provided with stirring blades at least in the water distribution area to achieve uniform water distribution or backwashing; the agitator is a hyperbolic stirring device made of glass fiber reinforced plastic.

7. The method for simultaneous anaerobic ammonium oxidation denitrification and phosphorus removal according to claim 2, characterized in that: The packing fixed bed is composed of a packing intercepting sieve plate, a supporting structure and a pool body; the packing intercepting sieve plate is a stainless steel plate with uniform holes, the supporting structure is located below the packing intercepting sieve plate and is composed of angle steel or steel section; the packing intercepting sieve plate is a detachable structure; the packing filling rate of the fixed bed is 60-80% by volume.

8. The method for simultaneous anaerobic ammonium oxidation denitrification and phosphorus removal according to claim 7, characterized in that: The intercepting screen plate is arranged below 0.5 m from the outlet channel of the anaerobic ammonia oxidation tank, and the opening rate of the intercepting screen plate is 30-35% of the area of ​​the screen plate.

9. The method for simultaneous anaerobic ammonium oxidation denitrification and phosphorus removal according to claim 2, characterized in that: The outlet channel of the sedimentation tank and the outlet channel of the anaerobic ammonia oxidation tank are both triangular weir plate outlet water collection systems.

10. The method for simultaneous anaerobic ammonium oxidation denitrification and phosphorus removal according to claim 2, characterized in that: The anaerobic ammonium oxidation pool is backwashed once every two weeks. The backwash water is the effluent from the clean water pool, which enters the anaerobic ammonium oxidation pool through the effluent return pipe. The backwashing time is 10 to 15 minutes, and the backwashing intensity is 10 to 15 L / (m 2 .S).

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