Wastewater denitrification and phosphorus removal equipment

Abstract

A highly efficient wastewater nitrogen and phosphorus removal system and its control and operation method are disclosed. The treatment system includes a pretreatment biochemical reactor, an intermediate tank, and an anammox-coupled denitrification reactor. The pretreatment biochemical reactor is equipped with an anammox digestion chamber, an aerobic nitrification chamber, and a short-cut denitrification chamber. Anammox digestion and phosphorus release reactions occur in the anammox chamber, aerobic nitrification and phosphorus uptake reactions occur in the aerobic nitrification chamber, and short-cut denitrification reactions occur in the short-cut denitrification chamber. Through real-time monitoring of the intermediate tank and flexible adjustment of water quality, as well as replenishment of supernatant, the system provides the NH4+ and NO2- substrates required for the anammox reaction and the COD for the subsequent denitrification reaction. Different functionally dominant bacterial communities are independently separated into different reaction units for nitrogen, phosphorus, and carbon removal, achieving efficient degradation and deep denitrification of nitrogen and phosphorus-containing raw water. The system is characterized by its resistance to shock loads and stable operation.

Description

Technical Field

[0001] This invention relates to biological wastewater treatment, and more particularly to a wastewater denitrification and phosphorus removal device suitable for wastewater with high chemical oxygen demand and high ammonia nitrogen, such as landfill leachate, aquaculture wastewater, and sludge digestion liquid. Background Technology

[0002] With the continuous expansion of urban scale and population, the scale and quantity of garbage and livestock wastewater generated have increased significantly, leading to a continuous increase in sludge digestion liquid from wastewater treatment and disposal processes. This type of wastewater is characterized by high concentrations of chemical oxygen demand (COD), high concentrations of ammonia nitrogen, and complex compositions of toxic and harmful substances. It also exhibits poor biodegradability and is difficult to treat. Consequently, conventional wastewater treatment processes often result in unstable effluent quality and failure to meet standards.

[0003] Currently, the main treatment method is "pretreatment + biochemical reaction + advanced treatment". Pretreatment often uses physicochemical methods as a pretreatment step, requiring the addition of chemical agents and large mixing devices to homogenize the water and agents, resulting in high power consumption and chemical costs. Advanced treatment often uses membrane technology, but membranes are expensive and have low durability, easily fouled by small-molecule proteins and organic matter in the raw water, causing membrane pore blockage. However, if untreated raw water is directly subjected to biochemical treatment, it can easily lead to microbial poisoning during the biochemical reaction, affecting the treated water quality. Facing increasingly stringent discharge standards and higher standards for water treatment processes that synergistically reduce pollution and carbon emissions, anaerobic ammonia oxidation (ANAO) is an emerging wastewater treatment technology with unique cost-reduction and efficiency-enhancing characteristics. This process is also easily combined with other biological denitrification processes, with short-cut denitrification coupled with ANAO being a typical example, providing a stable supply of ammonium ions (NH4) for the ANAO reaction. + and nitrite nitrogen ions NO2 - Reaction substrate. To overcome the shortcomings of traditional biological nitrogen removal, anaerobic ammonia oxidation is performed after the phosphorus removal process, in two separate reaction tanks, simultaneously achieving efficient nitrogen and phosphorus removal. During the anaerobic ammonia oxidation process, approximately 11% of the total nitrogen (TN) is converted into nitrate ions (NO3). - However, current methods are insufficient to achieve deep nitrogen removal. Therefore, to improve the nitrogen removal efficiency of anaerobic ammonia oxidation (ANAO) technology, it is combined with denitrification. The nitrate byproduct of ANAO can be metabolized and degraded by denitrifying bacteria, acting as an electron acceptor. However, the use of multiple different biological nitrogen-removing bacteria for cross-feeding results in inconsistent growth characteristics among the bacterial communities, making them susceptible to environmental influences and difficult to operate stably, thus limiting the widespread adoption in engineering applications. Existing technologies for treating wastewater with high concentrations of chemical oxygen demand (COD) and ammonium require large floor space, high initial investment, and high operating and maintenance costs, which is detrimental to meeting increasingly stringent wastewater treatment standards for upgrading and retrofitting. Summary of the Invention

[0004] The present invention aims to solve the problems of high chemical oxygen demand (COD) and high ammonia nitrogen wastewater, such as landfill leachate, aquaculture wastewater, and anaerobic digestion liquid, which are difficult to treat, have unstable operation, and high treatment costs. It provides a wastewater denitrification and phosphorus removal device suitable for high COD and high ammonia nitrogen wastewater such as landfill leachate, aquaculture wastewater, and sludge digestion liquid.

[0005] The wastewater nitrogen and phosphorus removal device of the present invention is characterized in that the device comprises a pretreatment biochemical reaction device, an intermediate water tank, and an anaerobic ammonia oxidation coupled denitrification reaction device, wherein the pretreatment biochemical reaction device, the intermediate water tank, and the anaerobic ammonia oxidation coupled denitrification reaction device are connected sequentially; wherein:

[0006] The pretreatment biochemical reaction device includes an anaerobic digestion reaction chamber, an aerobic nitrification reaction chamber, and a short-cut denitrification reaction chamber. These chambers are sequentially connected via inlet pipes. The outlet of the short-cut denitrification reaction chamber is connected to an intermediate water tank. The top of the anaerobic digestion reaction chamber is connected to the intermediate water tank via a water supply pipe. Suspended packing materials are installed in all three chambers. Exhaust vents are located at the top of all three chambers.

[0007] The anammox coupled denitrification reactor is cylindrical with a conical bottom. It is equipped with a mesh perforated baffle, which divides the interior into upper and lower sections. The upper section is the anammox coupled denitrification reaction chamber, and the lower section is the anammox reaction chamber. The intermediate water tank is connected to the anammox coupled denitrification reaction chamber and the anammox reaction chamber through water supply pipes. A peristaltic pump is installed on the water supply pipes.

[0008] The intermediate water tank is equipped with ammonium nitrogen sensors and nitrite nitrogen sensors, both of which are connected to the water quality controller. The inlet of the anaerobic digestion reaction chamber is located at the bottom, while the inlets of the aerobic nitrification reaction chamber and the short-cut denitrification reaction chamber are located at the top. An aeration disc is also installed at the bottom of the aerobic nitrification reaction chamber, and the aeration disc is connected to the blower through an air inlet pipe.

[0009] A drain solenoid valve is installed at the outlet of the short-cut denitrification reaction chamber, which drains the liquid from the short-cut denitrification reaction chamber to the intermediate water tank.

[0010] The inner wall of the anammox-coupled denitrification reactor is made of heat-insulating material, and the angle between the inner wall and the mesh perforated baffle is 60°. The height-to-diameter ratio of the anammox-coupled denitrification reactor is 6, and the volume ratio of the anammox reaction chamber to the anammox-coupled denitrification reaction chamber is 1.3:1. The anammox-coupled denitrification reaction chamber is filled with lightweight porous packing material, and the packing material volume accounts for 70-80% of the volume of the anammox-coupled denitrification reaction chamber. The anammox reaction chamber is filled with anammox granular sludge, and the sludge volume accounts for 40-60% of the volume of the anammox reaction chamber.

[0011] The peristaltic pump is connected to a peristaltic controller, which controls the working state of the peristaltic pump. The peristaltic controller, water quality controller, and drain solenoid valve are all connected to a PLC controller via wires, and the PLC controller is connected to a computer.

[0012] The operation process of the wastewater denitrification and phosphorus removal device is as follows:

[0013] 1) Start-up of the coupled system:

[0014] (1) Start-up of anaerobic digestion coupled with aerobic nitrification and simultaneous biological phosphorus removal reaction: The sludge from the anaerobic and aerobic tanks of the urban sewage treatment plant is used as the inoculation object. The sludge inoculated in the urban anaerobic tank corresponds to the anaerobic digestion reaction chamber of the reactor, and the sludge inoculated in the urban aerobic tank corresponds to the aerobic nitrification reaction chamber of the reactor. The concentration of the inoculated sludge is 5000-7500 mg / L, and the sludge layer volume accounts for 35%-50% of the reaction chamber, respectively. The dissolved oxygen (DO) in the aerobic nitrification reaction chamber is controlled to be greater than 2 mg / L, and the sludge age (SRT) is 8-12 days. Under the above conditions, the reactor is operated to acclimate and enrich the anaerobic digestion bacteria and nitrifying bacteria. When the chemical oxygen demand degradation rate of the effluent reaches more than 70%, the nitrate accumulation rate of the effluent reaches more than 80%, and the phosphorus removal rate reaches more than 85%, it indicates that the anaerobic digestion coupled with aerobic nitrification and simultaneous biological phosphorus removal reaction has been successfully started.

[0015] (2) Start-up of short-cut denitrification reaction: Inoculate the sludge from the anaerobic tank of the municipal wastewater treatment plant into the short-cut denitrification reaction chamber of the reactor. The concentration of the inoculated sludge is 5000-7500 mg / L, and the sludge layer volume accounts for 35%-50% of the short-cut denitrification reaction chamber. The dissolved oxygen is controlled to be less than 0.2 mg / L. Run the reactor under the above conditions to acclimate and enrich the short-cut denitrifying bacteria. When the nitrite accumulation rate in the effluent reaches more than 80%, it indicates that the short-cut denitrification reaction has been successfully started.

[0016] (3) Start-up of anaerobic ammonia oxidation coupled with denitrification: Anaerobic ammonia oxidation granular sludge from a laboratory and sludge from an anaerobic tank in a municipal wastewater treatment plant were used as inoculum. The anaerobic ammonia oxidation granular sludge and the sludge from the anaerobic tank of the municipal wastewater treatment plant were mixed at a ratio of 2:1. The average particle size of the anaerobic ammonia oxidation granular sludge was 0.2-0.5 mm, the inoculum sludge concentration was 5000-7500 mg / L, and the hydraulic retention time (HRT) was 1-4 h. During the cultivation and acclimatization process, artificially simulated wastewater was introduced into the anaerobic ammonia oxidation coupled with denitrification device. The ratio of ammonia nitrogen to nitrite nitrogen was... =1:(1-1.5), the organic carbon source is sodium acetate with a concentration controlled at 30-80 mg / L, and the inorganic carbon source is potassium bicarbonate (KHCO3) with a concentration controlled at 1-1.5 g / L. The pH range is adjusted to 7.0-7.5 to create a slightly alkaline environment. Under the above conditions, the reaction device is operated to acclimate and enrich anaerobic ammonia-oxidizing bacteria and denitrifying bacteria. When the effluent ammonia nitrogen removal rate reaches more than 95%, the effluent nitrite removal rate reaches more than 95%, and the chemical oxygen demand removal rate reaches more than 90%, it indicates that the anaerobic ammonia oxidation coupled with denitrification reaction has been successfully started.

[0017] 2) Operation of the coupled system after startup:

[0018] Raw water enters the biochemical reaction device along the water flow direction;

[0019] (1) First, it passes through the anaerobic digestion reaction chamber, where anaerobic digestive bacteria degrade organic matter in the raw water and consume a large amount of chemical oxygen demand to reduce the inhibition of organic load in the subsequent reaction chamber. Polyphosphate-accumulating bacteria carry out anaerobic phosphorus release and storage of internal carbon source PHAs, and then enter the aerobic nitrification reaction chamber.

[0020] (2) After entering the aerobic nitrification reaction chamber, turn on the aeration pump and use the aeration disc to aerate evenly in the aerobic nitrification reaction chamber, control the dissolved oxygen concentration to be greater than 2 mg / L, and carry out aerobic nitrification and aerobic phosphorus uptake processes simultaneously.

[0021] (3) After being treated in the aerobic nitrification reaction chamber, the water flows into the short-cut denitrification reaction chamber. The dissolved oxygen concentration is controlled to be less than 0.2 mg / L for short-cut denitrification reaction. After that, the raw water flows into the intermediate water tank through the drain solenoid valve. At the same time, the supernatant from the top of the aerobic nitrification reaction chamber is added to the intermediate water tank to maintain the water quality and ammonia nitrogen concentration in the intermediate water tank at 60-120 mg / L, ammonia nitrogen: nitrite nitrogen = 1: (1-1.5), chemical oxygen demand concentration is controlled at 30-80 mg / L, potassium bicarbonate is used as the inorganic carbon source and the concentration is controlled at 1-1.5 g / L, and potassium bicarbonate is used to adjust the pH range to 7.0-7.5 neutral to slightly alkaline environment.

[0022] (4) After the ammonia nitrogen and nitrite nitrogen stored in the intermediate water tank are balanced, they are pumped into the bottom of the anaerobic ammonia oxidation coupled denitrification reactor by a peristaltic pump. The reactor does not actively discharge sludge during operation. The hydraulic retention time (HRT) is 1-4 hours. The dissolved oxygen concentration in the anaerobic environment is maintained at <0.2 mg / L. The reactor is sealed and the temperature is controlled at 30±4℃. The ammonium nitrogen sensor and nitrite nitrogen sensor are used for real-time monitoring. The amount of supernatant in the aerobic nitrification reaction chamber is dynamically adjusted according to the concentration of ammonia nitrogen and nitrite nitrogen in the intermediate water tank to ensure that the balanced water quality meets the ammonia nitrogen: nitrite nitrogen = 1: (1-1.5) reaction substrate required for the anaerobic ammonia oxidation reaction. The chemical oxygen demand concentration provided is controlled at 30-80 mg / L to meet the subsequent denitrification reaction. The total phosphorus in the final effluent does not exceed 6 mg / L.

[0023] Technical principles and advantages of the present invention:

[0024] Wastewater containing high ammonia nitrogen concentration and high chemical oxygen demand concentration is treated by anaerobic digestion. Anaerobic bacteria decompose a large amount of chemical oxygen demand in the landfill leachate, thereby removing the influence of organic matter on subsequent biochemical reactions. During this process, polyphosphate bacteria simultaneously carry out anaerobic phosphorus release and store internal carbon source PHAs. The specific reaction principle of anaerobic digestion is: (1) hydrolysis and fermentation stage; (2) hydrogen production and acetic acid production stage; (3) methanogenesis stage; The specific principle of polyphosphate bacteria anaerobic phosphorus release: Under anaerobic conditions with sufficient phosphate and organic phosphorus, polyphosphate bacteria release phosphate in their bodies through special cellular metabolic mechanisms, produce adenine nucleoside triphosphate ATP, and rapidly absorb and degrade organic matter until it is converted into an internal carbon source and stored in the cell;

[0025] Then, aerobic nitrification is employed, utilizing nitrifying bacteria to convert ammonia nitrogen into nitrate under aerobic conditions, while polyphosphate-accumulating bacteria simultaneously carry out aerobic polyphosphate accumulation. The specific reaction principle of aerobic nitrification is as follows: NH4 + +2O2→NO3 - +H₂O+2H + The specific principle of anaerobic phosphorus release by polyphosphate-accumulating bacteria: Under aerobic conditions, polyphosphate-accumulating bacteria degrade their stored internal carbon sources through a special metabolic mechanism of cells, generating energy for excessive phosphorus uptake and cell synthesis, forming high-phosphorus-concentration sludge, which is discharged from the system along with the remaining sludge, thereby achieving the purpose of phosphorus removal.

[0026] Then, short-cut denitrification is used, which utilizes short-cut denitrifying bacteria to limit the conversion of nitrates to nitrites in an anaerobic environment.

[0027] ˉˉ

[0028] The specific reaction principle of salt production is: 3NO3 + CH3OH → 3NO2 + CO2 + 2H2O;

[0029] Finally, anaerobic ammonia oxidation and denitrification are employed. This process utilizes the ammonia nitrogen and nitrite remaining from the short-cut nitrification treatment to anaerobically oxidize into nitrogen gas for stripping. The specific reaction principle is as follows: NH4 + +1.32NO2 - +0.066HCO3 - +0.13H + →0.26NO3 - +1.02N2+0.066CH2O 0.5 N 0.15 +2.03H2O;

[0030] NO3 produced by anaerobic ammonium oxidation - and NO3 residue from short-range denitrification - and NO2 - , will NO X - Convert to N 2 The specific reaction principle of the stripping process is: 2NO3 - +10e+12H + →N2 + 6H2O, 2H+ + 2NO2 - +6e→N2+3H 2 O+CO2.

[0031] Based on the characteristics of nitrogen and phosphorus-containing wastewater with high chemical oxygen demand (COD), this invention features a pretreatment reaction device that can effectively degrade toxic, harmful, and difficult-to-treat substances, providing a stable operating environment for subsequent biochemical units. It boasts a high degree of automation, allowing for flexible adjustment of the raw water influent flow rate according to changes in effluent quality, dynamically controlling the impact of water quality load on water treatment operations, and achieving a short-cut denitrification / nitrification pathway to provide the necessary NH4+ for subsequent anaerobic ammonia oxidation reactions. + and NO2 - The substrate facilitates control over the actual operation of wastewater treatment plants; the separate arrangement of various biological units enables synergistic denitrification by functional microbial communities such as polyphosphate-accumulating bacteria, nitrifying bacteria, short-range denitrifying bacteria, AnAOB, and denitrifying bacteria, avoiding the limitation of AnAOB by subsequent organic matter, and also solving the problem of NO2 retention in the Anammox reaction and reaction substrate. - and NO3 -This significantly improves the TN removal rate of the system; the device has a small footprint, low operating and maintenance costs, and is less likely to generate residual sludge, saving sludge disposal costs. It is also easy to place and construct near different types of wastewater treatment facilities for integration. The anaerobic ammonia oxidation coupled with denitrification reactor has a large height-to-diameter ratio, and the balanced water quality through segmented influent and replenishment helps improve the degradation effect of key functional microorganisms on the reaction substrate. The resulting microbial community exhibits a clear distribution of denitrification reaction functional zones. Furthermore, the reactor is equipped with mesh baffles filled with packing material to form a biofilm, preventing the retention of functional microorganisms from sludge loss. Simultaneously, it can also remove NO3 generated by the anaerobic ammonia oxidation reaction at the bottom of the reactor. - Further degradation was carried out, achieving denitrification efficiency in wastewater filtrate. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the wastewater denitrification and phosphorus removal device of the invention.

[0033] Figure 2 This is a schematic diagram of the process flow of the present invention.

[0034] Figure 3 This is a graph showing the changes in ammonia nitrogen in the influent water quality.

[0035] Figure 4 This is a graph showing the changes in influent water quality due to nitrite nitrogen.

[0036] Figure 5 This is a graph showing the changes in total nitrogen in the influent water quality.

[0037] Figure 6 The graph shows the removal rates of ammonia nitrogen, chemical oxygen demand, and total phosphorus.

[0038] Figure 7 This is a graph showing the removal rate of Comparative Example 1.

[0039] Figure 8 This is a graph showing the removal rate of Comparative Example 2.

[0040] Figure 9 This is a graph showing the removal rate of Comparative Example 3.

[0041] Wherein: 1-Inlet; 2-Pretreatment biochemical reaction device; 3-Intermediate water tank; 4-Anaerobic ammonia oxidation coupled denitrification reaction device; 5-Anaerobic digestion reaction chamber; 6-Aerobic nitrification reaction chamber; 7-Short-cut denitrification reaction chamber; 8-Suspended packing; 9-Inlet of aerobic nitrification reaction chamber; 10-Blower; 11-Air inlet pipe; 12-Aeration disc; 13-Sludge discharge port; 14-Inlet of short-cut aerobic nitrification reaction chamber; 15-Drainage solenoid valve; 16-Exhaust port; 17-Water supply pipe; 18-NH4 +- -N sensor; 19-NO2 --N Sensor; 20 Peristaltic pump; 21 Anaerobic ammonia oxidation reaction chamber; 22 Anaerobic ammonia oxidation coupled with denitrification reaction chamber; 23 Mesh perforated baffle; 24 Second inlet; 25 Lightweight porous packing; 26 Outlet; 27 Water quality controller; 28 Peristaltic pump controller; 29 PLC controller; 30 Computer. Detailed Implementation

[0042] Example 1: A wastewater nitrogen and phosphorus removal device, comprising a pretreatment biochemical reaction unit, an intermediate water tank, and an anaerobic ammonia oxidation coupled denitrification reaction unit, wherein the pretreatment biochemical reaction unit, the intermediate water tank, and the anaerobic ammonia oxidation coupled denitrification reaction unit are connected sequentially; wherein:

[0043] The pretreatment biochemical reaction device includes an anaerobic digestion reaction chamber, an aerobic nitrification reaction chamber, and a short-cut denitrification reaction chamber. These chambers are sequentially connected via inlet pipes. The outlet of the short-cut denitrification reaction chamber is connected to an intermediate water tank. The top of the anaerobic digestion reaction chamber is connected to the intermediate water tank via a water supply pipe. Suspended packing materials are installed in all three chambers. Exhaust vents are located at the top of all three chambers.

[0044] The anammox coupled denitrification reactor is cylindrical with a conical bottom. It is equipped with a mesh perforated baffle, which divides the interior into upper and lower sections. The upper section is the anammox coupled denitrification reaction chamber, and the lower section is the anammox reaction chamber. The intermediate water tank is connected to the anammox coupled denitrification reaction chamber and the anammox reaction chamber through water supply pipes. A peristaltic pump is installed on the water supply pipes.

[0045] The intermediate water tank is equipped with ammonium nitrogen and nitrite nitrogen sensors, both of which are connected to a water quality controller. The water quality controller uses a Bebur BT-7000 multi-parameter controller. The inlet of the anaerobic digestion reaction chamber is located at the bottom, while the inlets of the aerobic nitrification reaction chamber and the short-cut denitrification reaction chamber are located at the top. An aeration disc is also installed at the bottom of the aerobic nitrification reaction chamber, and the aeration disc is connected to a blower through an air inlet pipe.

[0046] A drain solenoid valve is installed at the outlet of the short-range denitrification reaction chamber. The drain solenoid valve drains the liquid from the short-range denitrification reaction chamber to the intermediate water tank. The drain solenoid valve uses the BZ202 model drain controller from Bizhen Digital Technology Co., Ltd.

[0047] The inner wall of the anammox-denitrification coupled reactor is made of heat-insulating material, and the angle between the inner wall and the mesh perforated baffle is 60°. The height-to-diameter ratio of the anammox-denitrification coupled reactor is 6, and the volume ratio of the anammox reaction chamber to the anammox-denitrification reaction chamber is 1.3:1. The anammox-denitrification reaction chamber is filled with lightweight porous packing material, and the packing material volume accounts for 70-80% of the volume of the anammox-denitrification reaction chamber. The anammox reaction chamber is filled with anammox granular sludge, and the sludge volume accounts for 40-60% of the volume of the anammox reaction chamber.

[0048] The wastewater denitrification and phosphorus removal device has a peristaltic pump connected to a peristaltic controller. The peristaltic controller controls the working status of the peristaltic pump. The peristaltic controller is the Anchuanda Intelligent Constant Pressure Controller HY920A from Shenzhen Anchuanda Technology Co., Ltd. The peristaltic controller, water quality controller, and drainage solenoid valve are all connected to a PLC controller via wires. The PLC controller is a Siemens S7-1200 controller. The PLC controller is connected to a computer, and the control software with "Software Copyright Registration No. 2472076" is installed on the computer to complete the control operation.

[0049] The wastewater nitrogen and phosphorus removal device of the present invention operates as follows:

[0050] 1) Start-up of the coupled system:

[0051] (1) Start-up of anaerobic digestion coupled with aerobic nitrification and simultaneous biological phosphorus removal reaction: The sludge from the anaerobic and aerobic tanks of the urban sewage treatment plant is used as the inoculation object. The sludge inoculated in the urban anaerobic tank corresponds to the anaerobic digestion reaction chamber of the reactor, and the sludge inoculated in the urban aerobic tank corresponds to the aerobic nitrification reaction chamber of the reactor. The concentration of the inoculated sludge is 5000-7500 mg / L, and the sludge layer volume accounts for 35%-50% of the reaction chamber, respectively. The dissolved oxygen (DO) in the aerobic nitrification reaction chamber is controlled to be greater than 2 mg / L, and the sludge age (SRT) is 8-12 days. Under the above conditions, the reactor is operated to acclimate and enrich the anaerobic digestion bacteria and nitrifying bacteria. When the chemical oxygen demand degradation rate of the effluent reaches more than 70%, the nitrate accumulation rate of the effluent reaches more than 80%, and the phosphorus removal rate reaches more than 85%, it indicates that the anaerobic digestion coupled with aerobic nitrification and simultaneous biological phosphorus removal reaction has been successfully started.

[0052] (2) Start-up of short-cut denitrification reaction: Inoculate the sludge from the anaerobic tank of the municipal wastewater treatment plant into the short-cut denitrification reaction chamber of the reactor. The concentration of the inoculated sludge is 5000-7500 mg / L, and the volume of the sludge layer accounts for 35%-50% of the volume of the short-cut denitrification reaction chamber. The dissolved oxygen is controlled to be less than 0.2 mg / L. Under the above conditions, run the reactor to acclimate and enrich the short-cut denitrifying bacteria. When the nitrite accumulation rate in the effluent reaches more than 80%, it indicates that the short-cut denitrification reaction has been successfully started.

[0053] (3) Start-up of anammox coupled with denitrification: Anammox granular sludge from a laboratory and sludge from an anaerobic tank in a municipal wastewater treatment plant were used as inoculum. The laboratory-produced anammox granular sludge, containing the strain Candidatu Kuenenia, was purchased from Qinggang Environmental Protection. The anammox granular sludge was mixed with the sludge from the municipal wastewater treatment plant at a 2:1 ratio. The average particle size of the anammox granular sludge was 0.2-0.5 mm, the inoculum concentration was 5000-7500 mg / L, and the hydraulic retention time (HRT) was 1-4 h. Artificial simulated wastewater was used during the cultivation and acclimatization process and entered the anammox coupled with denitrification device. The main components of the artificial simulated wastewater were NH4Cl, NaNO2, and NaHCO3. + -N and NO2 -- The concentrations of nitrogen (N) were 120 and 160 mg / L, respectively. 0.25 ml of trace element I and 0.5 ml of trace element II were added per liter of influent, respectively. Trace element I consisted of: FeCl₂·4H₂O, 5 g / L; ZnCl₂, 0.2 g / L; MnCl₂·4H₂O, 1.24 g / L; and (NH₄)₆Mo₇O₇. 24 • 4H₂O, 0.24 g / L; CoCl₂·4H₂O, 0.32 g / L; CuCl₂·4H₂O, 0.32 g / L; NiCl₂·4H₂O, 0.24 g / L; H₃BO₃, 0.08 g / L; Na₂SeO₃·5H₂O, 0.10 g / L; MgSO₄·4H₂O, 9 g / L; CaCl₂·2H₂O, 8 g / L; EDTA, 1 g / L; Trace element II component: K₂HPO₄, 21. 2 g / L of ammonia nitrogen and 53.6 g / L of K2HPO4; ammonia nitrogen: nitrite nitrogen = 1:(1-1.5); the organic carbon source is sodium acetate with a concentration controlled at 30-80 mg / L, and the inorganic carbon source is potassium bicarbonate (KHCO3) with a concentration controlled at 1-1.5 g / L. Potassium bicarbonate is used to adjust the pH range to a slightly alkaline environment of 7.0-7.5. Under these conditions, the reaction apparatus is operated to acclimate and enrich anaerobic ammonia-oxidizing bacteria and denitrifying bacteria. Ammonia nitrogen (NH4) emitted during startup is periodically monitored. + -N, Nitrite nitrogen NO2 - The concentrations and removal rates of -N and total nitrogen (TN) in the influent and effluent are as follows: when the effluent ammonia nitrogen removal rate reaches more than 95%, the effluent nitrite removal rate reaches more than 95%, and the chemical oxygen demand (COD) removal rate reaches more than 90%, it indicates that the anaerobic ammonia oxidation coupled with denitrification reaction has been successfully started.

[0054] 2) Operation of the coupled system after startup:

[0055] Raw water enters the biochemical reaction unit, along the direction of water flow,

[0056] (1) First, it passes through the anaerobic digestion reaction chamber, where anaerobic digestive bacteria degrade organic matter in the raw water and consume a large amount of chemical oxygen demand to reduce the inhibition of organic load in the subsequent reaction chamber. Polyphosphate-accumulating bacteria carry out anaerobic phosphorus release and storage of internal carbon source PHAs, and then enter the aerobic nitrification reaction chamber.

[0057] (2) After entering the aerobic nitrification reaction chamber, turn on the aeration pump and use the aeration disc to aerate evenly in the aerobic nitrification reaction chamber, control the dissolved oxygen concentration to be greater than 2 mg / L, and carry out aerobic nitrification and aerobic phosphorus uptake processes simultaneously.

[0058] (3) After being treated in the aerobic nitrification reaction chamber, the raw water flows into the short-cut denitrification reaction chamber. The dissolved oxygen concentration is controlled to be less than 0.2 mg / L for short-cut denitrification reaction. Then, the raw water flows into the intermediate water tank through the drain solenoid valve. At the same time, the supernatant from the top of the anaerobic digestion reaction chamber is added to the intermediate water tank to maintain the water quality and ammonia nitrogen concentration in the intermediate water tank at 60-120 mg / L, ammonia nitrogen: nitrite nitrogen = 1: (1-1.5), chemical oxygen demand concentration is controlled at 30-80 mg / L, potassium bicarbonate is used as the inorganic carbon source and the concentration is controlled at 1-1.5 g / L. Potassium bicarbonate is used to adjust the pH range to 7.0-7.5 neutral to slightly alkaline environment.

[0059] (4) After the ammonia nitrogen and nitrite nitrogen stored in the intermediate water tank are balanced, they are pumped into the bottom of the anaerobic ammonia oxidation coupled denitrification reactor by a peristaltic pump. The reactor does not actively discharge sludge during operation. The HRT is 1-4 hours. The dissolved oxygen concentration in the anaerobic environment is maintained at <0.2 mg / L, and the reactor is sealed. The temperature is controlled at 30±4℃. Real-time monitoring is achieved using ammonium nitrogen and nitrite nitrogen sensors. The amount of supernatant in the aerobic nitrification reaction chamber is dynamically adjusted based on the ammonia nitrogen and nitrite nitrogen concentrations in the intermediate water tank to ensure that the balanced water quality meets the ammonia nitrogen:nitrite nitrogen = 1:(1-1.5) reaction substrate required for the anaerobic ammonia oxidation reaction. The provided chemical oxygen demand (COD) concentration is controlled at 30-80 mg / L to meet the subsequent denitrification reaction. The final effluent total phosphorus does not exceed 6 mg / L. The ammonia nitrogen removal rate, COD removal rate, and total phosphorus removal rate are measured as follows: Figure 6 As shown.

[0060] Comparative Example 1: A highly efficient wastewater nitrogen and phosphorus removal system and its control and operation method. Compared with Example 1, the landfill leachate in Example 1 is replaced with municipal wastewater, while the rest of the equipment and operation are the same as in Example 1; NH4 is detected. + -N removal rate, COD removal rate and TP removal rate are as follows: Figure 7 As shown.

[0061] Comparative Example 2: A highly efficient wastewater nitrogen and phosphorus removal system and its control and operation method. Compared with Example 1, the landfill leachate in Example 1 is replaced with sludge nitrification liquor, while the remaining equipment and operation methods are the same as in Example 1. NH4 detection. + -N removal rate, COD removal rate and TP removal rate are as follows: Figure 8 As shown.

[0062] Comparative Example 3: A highly efficient wastewater nitrogen and phosphorus removal system and its control and operation method. Compared with Example 1, the landfill leachate in Example 1 is replaced with aquaculture wastewater, while the remaining equipment and operation methods are the same as in Example 1. NH4 detection. + -N removal rate, COD removal rate and TP removal rate are as follows: Figure 9 As shown.

[0063] The comparative examples did not use landfill leachate from Example 1 as the treatment target. Instead, they employed one of the efficient wastewater denitrification and phosphorus removal systems and control methods described in Comparative Examples 1-3 to treat municipal wastewater from a residential community in Kunming, Yunnan Province, aquaculture wastewater, and sludge digestion liquid from a wastewater treatment plant. The effluent from the treatment methods in Example 1 and Comparative Examples 1-3 was then tested for water quality. The main water quality indicators of the effluent are shown in Table 1.

[0064] Table 1

[0065] project Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[NH3 + Concentration / mg / L]]> 1.6 5.4 2.1 2.1 <![CDATA[NO2 - Concentration / mg / L]]> 0.5 2.3 2.6 3.1 <![CDATA[NO3 - Concentration / mg / L]]> 0.7 1.9 0.5 0.7 TN concentration / mg / L 2.8 9.6 5.2 5.9 TP concentration / mg / L 0.8 0.7 1.2 1.8 COD concentration (mg / L) 2.3 1.1 5.5 4.6

[0066] As can be seen from the data recorded in the table above, compared with Example 1 and Comparative Examples 1-3, all can obtain better effluent quality and achieve the effect of deep treatment method, especially the landfill leachate treatment provided by Example 1 is the best.

Claims

1. A device for denitrification and dephosphorization of sewage, characterized in that The device comprises a pretreatment biochemical reaction device, an intermediate water tank and an anaerobic ammonia oxidation coupled denitrification reaction device, which are sequentially connected. The pretreatment biochemical reaction device comprises an anaerobic digestion reaction chamber, an aerobic nitrification reaction chamber and a short-cut denitrification reaction chamber, which are sequentially connected through connecting pipes. The anaerobic digestion reaction chamber, the aerobic nitrification reaction chamber and the short-cut denitrification reaction chamber are all provided with suspended fillers. The anaerobic ammonia oxidation coupled denitrification reaction device is in a cylindrical shape with a conical bottom and is internally provided with a meshed baffle with holes. The meshed baffle with holes divides the inside into an upper section and a lower section.

2. The device for removing nitrogen and phosphorus from sewage according to claim 1, characterized in that The upper section is an anaerobic ammonia oxidation coupled denitrification reaction chamber, and the lower section is an anaerobic ammonia oxidation reaction chamber.

3. The device for removing nitrogen and phosphorus from sewage according to claim 1, characterized in that The intermediate water tank is connected to the anaerobic ammonia oxidation coupled denitrification reaction chamber and the anaerobic ammonia oxidation reaction chamber through water supply pipes.

4. The device for removing nitrogen and phosphorus from sewage according to claim 1, characterized in that A peristaltic pump is arranged on the water supply pipes. The anaerobic digestion reaction chamber is provided with an ammonium nitrogen sensor and a nitrite nitrogen sensor, which are connected to a water quality controller. The water inlet of the aerobic nitrification reaction chamber and the short-cut denitrification reaction chamber is located at the upper part. The bottom of the aerobic nitrification reaction chamber is further provided with an aeration disc connected to a blower through an air inlet pipe. A drain electromagnetic valve is arranged on the water outlet of the short-cut denitrification reaction chamber. The drain electromagnetic valve drains the liquid in the short-cut denitrification reaction chamber to the intermediate water tank. The inner wall of the anaerobic ammonia oxidation coupled denitrification reaction device is made of heat-insulating material, and the included angle between the inner wall and the meshed baffle with holes is 60°. The height-diameter ratio of the anaerobic ammonia oxidation coupled denitrification reaction device is 6, and the volume ratio of the anaerobic ammonia oxidation reaction chamber to the anaerobic ammonia oxidation coupled denitrification reaction chamber is 1.3:

1. The anaerobic ammonia oxidation coupled denitrification reaction chamber is filled with lightweight porous fillers, and the volume of the fillers accounts for 70-80% of the volume of the anaerobic ammonia oxidation coupled denitrification reaction chamber. The anaerobic ammonia oxidation reaction chamber is filled with anaerobic ammonia oxidation granular sludge, and the volume of the granular sludge accounts for 40-60% of the volume of the anaerobic ammonia oxidation reaction chamber. The peristaltic pump is connected to a peristaltic controller, which controls the working state of the peristaltic pump. The peristaltic controller, the water quality controller and the drain electromagnetic valve are connected to a PLC controller through wires, and the PLC controller is connected to a computer. The operation process of the device is as follows: 1) Device start-up (1) Anaerobic digestion coupled with aerobic nitrification simultaneous biological phosphorus removal reaction start-up: The sludge in the anaerobic tank and the aerobic tank of the municipal wastewater treatment plant is used as the inoculation object, the sludge in the anaerobic tank is inoculated into the anaerobic digestion reaction chamber in the reaction device, and the sludge in the aerobic tank is inoculated into the aerobic nitrification reaction chamber in the reaction device, the sludge concentration is 5000-7500 mg / L, the sludge layer volume accounts for 35%-50% of the reaction chamber, the dissolved oxygen DO in the aerobic nitrification reaction chamber is controlled to be greater than 2 mg / L, and the sludge retention time SRT is 8-12 d; under the above conditions, the reaction device is operated, and the anaerobic digestion bacteria and nitrifying bacteria are domesticated and enriched, when the degradation rate of the effluent chemical oxygen demand is more than 70%, the nitrate accumulation rate of the effluent is more than 80%, and the phosphorus removal rate is more than 85%, it indicates that the anaerobic digestion coupled with aerobic nitrification simultaneous biological phosphorus removal reaction is successfully started; (2) Short-cut denitrification reaction start-up: The sludge in the anaerobic tank of the municipal wastewater plant is inoculated into the short-cut denitrification reaction chamber in the reaction device, the concentration of the inoculated sludge is 5000-7500 mg / L, the volume of the sludge layer accounts for 35%-50% of the short-cut denitrification reaction chamber, and the dissolved oxygen is controlled to be less than 0.2 mg / L; under the above conditions, the reaction device is operated, and the short-cut denitrification bacteria are domesticated and enriched, when the effluent nitrite accumulation rate is more than 80%, it indicates that the short-cut denitrification reaction is successfully started; (3) Anaerobic ammonia oxidation coupled with denitrification reaction start-up: The anaerobic ammonia oxidation granular sludge and the sludge in the anaerobic tank of the municipal wastewater plant are used as the inoculation object, the anaerobic ammonia oxidation granular sludge and the sludge in the anaerobic tank of the municipal wastewater plant are mixed and inoculated at a ratio of 2:1, the average particle size of the anaerobic ammonia oxidation granular sludge is 0.2-0.5 mm, the inoculated sludge concentration is 5000-7500 mg / L, and the hydraulic retention time HRT is 1-4 h; during the cultivation and domestication process, artificial simulated wastewater is used to enter the anaerobic ammonia oxidation coupled with denitrification reaction device, the ammonia nitrogen and nitrite nitrogen ratio is 1:(1-1.5), the organic carbon source is sodium acetate and the concentration is controlled at 30-80 mg / L, the inorganic carbon source is potassium bicarbonate KHCO3 and the concentration is controlled at 1-1.5 g / L, and the potassium bicarbonate is used to adjust the pH range to 7.0-7.5; under the above conditions, the reaction device is operated, and the anaerobic ammonia oxidation bacteria and denitrifying bacteria are domesticated and enriched, when the effluent ammonia nitrogen removal rate is more than 95%, the effluent nitrite removal rate is more than 95%, and the chemical oxygen demand removal rate is more than 90%, it indicates that the anaerobic ammonia oxidation coupled with denitrification reaction is successfully started; 2) Device start-up operation: (1) The raw water first passes through the anaerobic digestion reaction chamber, the anaerobic digestion bacteria degrade the organic matter in the raw water, consume a large amount of chemical oxygen demand, and reduce the inhibition of organic load on the subsequent reaction chamber, and the phosphorus accumulating bacteria perform the anaerobic phosphorus release and storage of internal carbon source PHAs process, and then enter the aerobic nitrification reaction chamber; (2) After entering the aerobic nitrification reaction chamber, the aeration pump is started, the aeration disc is used to uniformly aerate in the aerobic nitrification reaction chamber, the dissolved oxygen concentration is controlled to be greater than 2 mg / L, and the aerobic nitrification and aerobic phosphorus absorption processes are simultaneously performed; (3) After the treatment of the aerobic nitrification reaction chamber, the water flows into the short-cut denitrification reaction chamber, and the dissolved oxygen concentration is controlled to be less than 0.2 mg / L for short-cut denitrification reaction. Then the raw water flows into the intermediate water tank through the drain electromagnetic valve, and the supernatant at the top of the aerobic nitrification reaction chamber is supplemented into the intermediate water tank to maintain the stability of the water quality in the intermediate water tank. The water quality in the intermediate water tank is required to be: the ammonia nitrogen concentration is 60-120 mg / L, the ammonia nitrogen to nitrite nitrogen ratio is 1:(1-1.5), and the chemical oxygen demand concentration is controlled to be 30-80 mg / L. Potassium bicarbonate is added into the intermediate water tank as an inorganic carbon source, and the concentration is controlled to be 1-1.5 g / L, which provides carbon source for anaerobic ammonia oxidation bacteria and adjusts and maintains the pH of the intermediate water tank to be 7.0-7.5; (4) After the ammonia nitrogen and nitrite nitrogen balanced water quality stored in the intermediate water tank, it enters the anaerobic ammonia oxidation coupled denitrification reaction chamber bottom and the anaerobic ammonia oxidation reaction chamber bottom through the peristaltic pump at the same time. The reactor does not actively discharge sludge during operation, the hydraulic retention time HRT is 1-4 h, the dissolved oxygen concentration is maintained to be less than 0.2 mg / L in the anaerobic environment, and the reaction device is sealed. The temperature is controlled at 30±4℃. Real-time monitoring is realized by using ammonium nitrogen sensor and nitrite nitrogen sensor, and the supernatant water quantity of the aerobic nitrification reaction chamber entering the intermediate water tank is dynamically adjusted and controlled according to the ammonia nitrogen and nitrite nitrogen concentration in the intermediate water tank, so as to ensure that the balanced water quality meets the ammonia nitrogen to nitrite nitrogen ratio of 1:(1-1.5) required by anaerobic ammonia oxidation reaction. The chemical oxygen demand concentration in the intermediate water tank is controlled to be 30-80 mg / L to meet the subsequent denitrification reaction, and the total phosphorus in the final effluent of the device is not more than 6 mg / L.

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