Treatment system and method for wastewater with high ammonia nitrogen and low carbon nitrogen ratio

Abstract

The invention provides a high-ammonia-nitrogen low-carbon-nitrogen-ratio wastewater treatment system and method, and relates to the technical field of wastewater treatment.The treatment system comprises an aeration sedimentation tank set, a first-stage denitrification reactor, a water tank, a second-stage denitrification reactor and a nitrification tank which are sequentially arranged in the wastewater treatment direction; the aeration sedimentation tank group is used for removing organic matters and suspended matters in the sewage, reducing the concentration of metal ions and adjusting the pH value of the sewage; the primary denitrification reactor is communicated with the aeration sedimentation tank group and is used for carrying out short-cut nitrification reaction and anaerobic ammonia oxidation reaction; the top of the water tank is communicated with the primary denitrification reactor, and the bottom of the water tank is communicated with the secondary denitrification reactor through a first pipeline; the second-stage denitrification reactor is used for carrying out denitrification reaction coupling short-cut denitrification reaction and anaerobic ammonia oxidation reaction, and the second-stage denitrification reactor is provided with a first water outlet communicated with the first pipeline and a second water outlet communicated with the nitrification tank. The treatment system can ensure that high-ammonia-nitrogen low-carbon-nitrogen-ratio wastewater treatment reaches the nanotube standard.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a system and method for treating wastewater with high ammonia nitrogen and low carbon-nitrogen ratio. Background Art

[0002] High ammonia nitrogen and low carbon nitrogen ratio wastewater refers to wastewater with less organic carbon source available for microbial denitrification and higher ammonia nitrogen concentration. Common high ammonia nitrogen and low carbon nitrogen ratio wastewater mainly includes industrial wastewater generated by monosodium glutamate, fertilizer, coal chemical industry and other industries, aging garbage leachate generated by landfills, wastewater after anaerobic fermentation of livestock and poultry breeding, and dehydrated filtrate after anaerobic digestion of sludge in urban sewage treatment plants, all of which contain high concentrations of ammonia nitrogen.

[0003] At present, traditional nitrification and denitrification denitrification technology is the most widely used. However, when treating high-ammonia nitrogen and low carbon-nitrogen ratio wastewater, traditional nitrification and denitrification technology has obvious shortcomings. First, the nitrification process requires a large amount of oxygen supply and high energy consumption. The aeration system of a traditional sewage treatment plant accounts for about 50%-55% of the total electricity consumption of the sewage treatment plant. When treating high-ammonia nitrogen wastewater, the infrastructure investment and energy consumption will increase significantly; secondly, low carbon-nitrogen ratio wastewater has high ammonia nitrogen and insufficient organic carbon source, so additional carbon source needs to be added to meet the needs of the microbial denitrification process, which increases the operating cost and may cause secondary pollution.

[0004] In response to the above problems, the denitrification technology of the short-cut nitrification-anaerobic ammonium oxidation process is a new biological denitrification technology for treating wastewater with high ammonia nitrogen and low carbon-nitrogen ratio. Compared with the traditional nitrification-denitrification process, this process can reduce the aeration volume by 60%, does not require an organic carbon source, and has a low sludge yield (about 90% reduction). Therefore, wastewater with high ammonia nitrogen and low carbon-nitrogen ratio characteristics is suitable for denitrification treatment using the short-cut nitrification-anaerobic ammonium oxidation technology. However, there will still be residual nitrate nitrogen in the effluent of the short-cut nitrification-anaerobic ammonium oxidation process. This is because nitrate nitrogen by-products are produced in the anaerobic ammonium oxidation process, accounting for 11% of the amount of ammonia nitrogen removed. Therefore, the total nitrogen control standard (70 mg / L) and industry drainage standard (generally requiring 40 mg / L) cannot be met by the short-cut nitrification-anaerobic ammonium oxidation process alone. Summary of the invention

[0005] The purpose of the present invention is to provide a system and method for treating wastewater with high ammonia nitrogen and low carbon-nitrogen ratio, which can ensure that the treatment of wastewater with high ammonia nitrogen and low carbon-nitrogen ratio meets the management standard.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a treatment system for high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater, comprising an aeration sedimentation tank group, a primary denitrification reactor, a water tank, a secondary denitrification reactor and a nitrification tank sequentially arranged along the wastewater treatment direction;

[0008] The aeration sedimentation tank group is used to remove organic matter and suspended solids in sewage, reduce metal ion concentration and adjust the pH value of sewage;

[0009] The primary denitrification reactor is connected to the aeration sedimentation tank group, and the primary denitrification reactor is used to perform short-cut nitrification reaction and anaerobic ammonium oxidation reaction;

[0010] The top of the water tank is connected to the primary denitrification reactor, and the bottom of the water tank is connected to the secondary denitrification reactor through a first pipeline, and the first pipeline is also used to communicate with a carbon source;

[0011] The secondary denitrification reactor is used to carry out a denitrification reaction coupled with a short-range denitrification reaction and an anaerobic ammonium oxidation reaction. The secondary denitrification reactor has a first water outlet connected to the first pipeline and a second water outlet connected to the nitrification tank. The nitrification tank is used to oxidize ammonia nitrogen in the wastewater into nitrate nitrogen.

[0012] Furthermore, the aeration sedimentation tank group includes a pre-aeration tank and a sedimentation tank;

[0013] The pre-aeration tank has an acid / alkali solution delivery port, and a first aeration device is provided at the bottom of the pre-aeration tank;

[0014] Furthermore, the primary denitrification reactor includes a tank body, an agitator, a second aeration device, a first filler assembly and a first precipitator, the second aeration device is installed at the bottom of the tank body, the first filler assembly is installed in the tank body and is located above the second aeration device, the agitator extends into the tank body, and the first precipitator is installed at the outlet of the tank body.

[0015] Furthermore, the first packing assembly includes a packing frame and a plurality of packing units placed in the packing frame, the packing frame is supported at the bottom of the cell body by a bracket, and the plurality of packing units are stacked layer by layer in a direction from the bottom of the cell body to the top;

[0016] In two adjacent layers of the packing units, the bottom of the packing unit of the upper layer is clamped to the top of the packing unit of the lower layer;

[0017] Each layer of the packing units includes multiple rows and columns of the packing units, and adjacent packing units are closely arranged.

[0018] Further, the packing unit comprises an outer frame, a packing body and a plurality of retaining frames;

[0019] The top of the outer frame is surrounded by a limiting cavity, and the limiting cavity is used for the bottom of the outer frame in the upper filling unit to extend into;

[0020] The plurality of retaining frames are installed in parallel and at intervals in the outer frame, and divide the space in the outer frame into a plurality of water passage chambers and a plurality of accommodating chambers distributed horizontally, and each of the accommodating chambers is provided with the filler body.

[0021] Furthermore, an adjustment component is connected between each of the baffles and the outer frame, and the adjustment component is used to adjust the distance between adjacent baffles.

[0022] Furthermore, the primary denitrification reactor also has an acid / alkali solution introduction port and / or a nutrient element introduction port.

[0023] Furthermore, the bottom of the water tank is conical.

[0024] Furthermore, the treatment system also includes a water outlet pool connected to the water outlet of the nitrification tank, the water outlet pool has a third water outlet and a fourth water outlet, the third water outlet is used to communicate with the pipe network, and the fourth water outlet is connected to the top of the water tank.

[0025] In a second aspect, the present invention further provides a method for treating high ammonia nitrogen and low carbon nitrogen ratio wastewater using the high ammonia nitrogen and low carbon nitrogen ratio wastewater treatment system described in the above scheme, comprising:

[0026] Discharging the wastewater into the aeration sedimentation tank group, removing organic matter and suspended solids in the wastewater, reducing the concentration of metal ions, and adjusting the pH value of the wastewater through the aeration sedimentation tank group;

[0027] Discharging the wastewater discharged from the aeration sedimentation tank group into the primary denitrification reactor, wherein the wastewater undergoes a short-cut nitrification reaction and an anaerobic ammonium oxidation reaction in the primary denitrification reactor;

[0028] The wastewater discharged from the primary denitrification reactor is discharged into the top of the water tank and discharged from the bottom of the water tank into the secondary denitrification reactor for denitrification reaction coupled with short-range denitrification reaction and anaerobic ammonium oxidation reaction;

[0029] The wastewater discharged from the secondary denitrification reactor is discharged into the nitrification tank, and the nitrification reaction is carried out in the nitrification tank to oxidize the ammonia nitrogen in the wastewater into nitrate nitrogen.

[0030] The system and method for treating high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided by the present invention can produce the following beneficial effects:

[0031] Compared with the prior art, the treatment system for high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided in the first aspect of the present invention adopts a treatment process of aeration sedimentation - primary denitrification - secondary denitrification - nitrification. In the above process, the bottom of the water tank can also collect the anaerobic ammonia-oxidizing bacteria brought out with the effluent from the primary denitrification reactor and enter the secondary denitrification reactor from the first pipeline with the inlet water, which can fully utilize the anaerobic ammonia-oxidizing bacteria resources. The wastewater in the secondary denitrification reactor can also be returned to the first pipeline, which can ensure that the treatment of high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater meets the pipe standard.

[0032] The method for treating high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided in the second aspect of the present invention adopts the treatment system for high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided in the first aspect of the present invention, thereby having all the beneficial effects of the treatment system for high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided in the first aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the structure of a system for treating wastewater with high ammonia nitrogen and low carbon-nitrogen ratio provided by an embodiment of the present invention;

[0035] Figure 2 A schematic structural diagram of a primary denitrification reactor provided in an embodiment of the present invention;

[0036] Figure 3 A front view of a first packing assembly (without a packing frame) provided in an embodiment of the present invention;

[0037] Figure 4 A side view of a first packing assembly (without a packing frame) provided in an embodiment of the present invention;

[0038] Figure 5 A side view of a packing unit provided in accordance with an embodiment of the present invention.

[0039] Icons: 1-aeration sedimentation tank group; 11-pre-aeration tank; 111-first aeration device; 12-sedimentation tank; 2-first denitrification reactor; 21-tank body; 22-agitator; 221-blade; 23-second aeration device; 24-filling unit; 241-outer frame; 2411-annular edge; 2412-outer frame; 2413-support frame; 242-filling body; 243-blocking frame; 244-water passage chamber; 245-accommodating chamber; 246-sleeve; 247-fastener; 25-first sedimentation tank; 26-bracket; 27-filling frame; 3-water tank; 4-secondary denitrification reactor; 5-nitrification tank; 6-first pipeline; 7-outlet tank; 8-regulating tank. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0044] The embodiment of the first aspect of the present invention is to provide a system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio, such as Figure 1As shown, it includes an aeration sedimentation tank group 1, a primary denitrification reactor 2, a water tank 3, a secondary denitrification reactor 4 and a nitrification tank 5 which are arranged in sequence along the wastewater treatment direction;

[0045] Aeration sedimentation tank group 1 is used to remove organic matter and suspended solids in sewage, reduce metal ion concentration and adjust the pH value of sewage;

[0046] The primary denitrification reactor 2 is connected to the aeration sedimentation tank group 1, and the primary denitrification reactor 2 is used for performing a short-cut nitrification reaction and an anaerobic ammonium oxidation reaction;

[0047] The top of the water tank 3 is connected to the primary denitrification reactor 2, and the bottom of the water tank 3 is connected to the secondary denitrification reactor 4 through the first pipeline 6, and the first pipeline 6 is also used to communicate with the carbon source;

[0048] The secondary denitrification reactor 4 is used to carry out a denitrification reaction coupled with a short-range denitrification reaction and an anaerobic ammonia oxidation reaction. The secondary denitrification reactor 4 has a first water outlet connected to the first pipeline 6 and a second water outlet connected to the nitrification tank 5. The nitrification tank 5 is used to oxidize ammonia nitrogen in the wastewater into nitrate nitrogen.

[0049] like Figure 1 As shown, when the treatment system for high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided by the present invention is used, the wastewater first enters the aeration sedimentation tank group 1, which can remove organic matter and suspended matter in the wastewater, reduce the metal ion concentration and adjust the pH value of the wastewater, and reduce the impact on various reactions in the primary denitrification reactor 2; then the wastewater enters the primary denitrification reactor 2, in which a short-range nitrification reaction and an anaerobic ammonia oxidation reaction are carried out; then the wastewater discharged from the primary denitrification reactor 2 enters the water tank 3 from the top of the water tank, and since the bottom of the water tank 3 is connected to the secondary denitrification reactor 4, the anaerobic ammonia oxidation bacteria brought out with the effluent of the primary denitrification reactor 2 can be collected and enter the secondary denitrification reactor 4 with the influent from the first pipeline 6, and at the same time, the first pipeline 6 is connected to the secondary denitrification reactor 4. 6. A carbon source is added to the sewage, and the wastewater undergoes a denitrification reaction coupled with a short-range denitrification reaction and an anaerobic ammonium oxidation reaction in the secondary denitrification reactor 4. Since the ammonia nitrogen concentration in the effluent of the primary denitrification reactor 2 is usually 50-150 mg / L, and it also contains nitrate nitrogen, the secondary denitrification reactor 4 can further remove ammonia nitrogen and nitrate nitrogen in the water; finally, the wastewater discharged from the secondary denitrification reactor 4 enters the nitrification tank 5. After the wastewater passes through the secondary denitrification, the main component of nitrogen in the wastewater is ammonia nitrogen. The nitrification tank 5 can oxidize the ammonia nitrogen in the wastewater into nitrate nitrogen. In the above process, the wastewater in the secondary denitrification reactor 4 can also return to the first pipeline 6 and enter the secondary denitrification reactor 4 again for a short-range denitrification reaction and an anaerobic ammonium oxidation reaction.

[0050] In the above process, it is necessary to explain in more detail that the primary denitrification reactor 2 mainly carries out short-range nitrification reaction and anaerobic ammonia oxidation reaction to remove ammonia nitrogen in the wastewater, and also removes organic matter (COD) to a certain extent. The reactor can be started by first inoculating or enriching ammonia-oxidizing bacteria (Ammonia-oxidizing bacteria, AOB), and then inoculating anaerobic ammonium oxidation (anaerobic ammonium oxidation, Anammox) or directly inoculating seed mud or biofilm filler similar to the operating project.

[0051] In addition, the secondary denitrification reactor 4 can be inoculated with denitrifying granular sludge, which mainly completes the denitrification reaction to remove nitrite nitrogen and nitrate nitrogen. In addition, a part of the anaerobic ammonia-oxidizing bacteria retained in the water tank 3 will enter the secondary denitrification reactor 4, or a small amount of anaerobic ammonia-oxidizing granular sludge will be inoculated at the initial start-up stage to be enriched in the reactor, and short-range denitrification reaction and anaerobic ammonia-oxidation reaction will occur, which can remove ammonia nitrogen and nitrate nitrogen in the incoming water. Therefore, the secondary denitrification reactor 4 will couple the two denitrification processes.

[0052] It should also be noted that the above-mentioned high ammonia nitrogen and low carbon nitrogen ratio wastewater treatment system is suitable for wastewater with an ammonia nitrogen concentration of 300-3000 mg / L, C / N <1, especially when C / N <0.5, the COD (Chemical Oxygen Demand) concentration is as low as possible, and the inlet water temperature needs to be between 25 and 38°C. When the temperature is too low or too high, heat exchange equipment needs to be added, such as silane tower wastewater in the photovoltaic industry, high ammonia nitrogen wastewater in coal chemical industry, and dehydrated filtrate of ordinary sludge anaerobic digestion.

[0053] The treatment system for high ammonia nitrogen and low carbon nitrogen ratio wastewater provided in the above embodiment has the following advantages:

[0054] 1. The above-mentioned high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater treatment system retains bacteria with different functions in different reactors, so that each species can exert its maximum function. Compared with the traditional AO (Anaerobic Oxic) process, the design load is high and the corresponding pool volume is reduced. At the same time, the autotrophic bacteria can maintain a high concentration in the system and are not easy to be eliminated;

[0055] 2. The treatment system for the wastewater with high ammonia nitrogen and low carbon nitrogen ratio is provided with a secondary denitrification reactor 4 and a nitrification tank 5. The anaerobic ammonia oxidation reaction in the primary denitrification reactor 2 can effectively reduce the operating cost in treating the wastewater with high ammonia nitrogen and low carbon nitrogen ratio. However, the process will produce nitrate nitrogen, and a part of ammonia nitrogen will remain in the system. Subsequent denitrification and nitrification can better solve this problem.

[0056] 3. The water tank 3 can recycle the anaerobic ammonium oxidizing bacteria and further exert their function in the secondary denitrification reactor 4, so as to fully utilize the anaerobic ammonium oxidizing bacteria resources;

[0057] 4. Denitrification granular sludge can be inoculated in the secondary denitrification reactor 4. Compared with the traditional AO process, it not only has a high volume load, better anaerobic conditions, and a low carbon source dosage. The C / N of the traditional AO carbon source addition is about 5, while the C / N of the reactor carbon source addition is 3-3.5.

[0058] In an optional embodiment, if Figure 1 As shown, along the wastewater treatment direction, a regulating tank 8 is provided upstream of the aeration sedimentation tank group 1. After the wastewater enters the regulating tank 8, it can be lifted to the aeration sedimentation tank group 1 by a lifting pump.

[0059] The structure of the aeration sedimentation tank group 1 is described in detail below:

[0060] In an optional embodiment, if Figure 1 As shown, the aeration sedimentation tank group 1 includes a pre-aeration tank 11 and a sedimentation tank 12; the pre-aeration tank 11 has an acid / alkali solution introduction port, and a first aeration device 111 is provided at the bottom of the pre-aeration tank 11; the sedimentation tank 12 has a coagulant introduction port and / or a flocculant introduction port.

[0061] In the above embodiment, the first aeration device 111 can remove some organic matter and suspended matter in the sewage, reducing the impact on the short-range nitrification reaction and anaerobic ammonia oxidation reaction in the primary denitrification reactor 2. In the case where the concentration of certain metal ions in the wastewater exceeds the standard, personnel can add alkali solutions such as sodium carbonate and sodium hydroxide into the pre-aeration tank 11 through the acid / alkali solution injection port to adjust the pH value of the sewage, remove the excessive metal ions, and control the pH of the sewage between 7.3 and 8.3, thereby reducing the impact on the subsequent process sections.

[0062] After pre-aeration by the first aeration device 111, personnel can add coagulant into the sewage through the coagulant introduction port, and / or add flocculant into the sewage through the flocculant introduction port to remove suspended matter in the water so that the suspended matter is controlled below 100 mg / L.

[0063] Among them, coagulants include aluminum salts, iron salts, polyferric sulfate, polyaluminum chloride, etc., and flocculants include polyaluminum ferric chloride, polyacrylamide (PAM), etc.

[0064] The structure of the primary denitrification reactor 2 is described in detail below:

[0065] In an optional embodiment, if Figure 2As shown, the primary denitrification reactor 2 includes a tank body 21, an agitator 22, a second aeration device 23, a first filler assembly and a first precipitator 25. The second aeration device 23 is installed at the bottom of the tank body 21, the first filler assembly is installed in the tank body 21 and is located above the second aeration device 23, the agitator 22 extends into the tank body 21, and the first precipitator 25 is installed at the outlet of the tank body 21.

[0066] Since the anaerobic ammonia-oxidizing bacteria inoculated in the primary denitrification reactor 2 are granular sludge, it is difficult to achieve a good mixing effect only by the second aeration device 23, especially in the early stage of biofilm formation or when the nitrite concentration in the system is high and aeration is not possible, the agitator 22 can achieve a better stirring effect.

[0067] In addition, adding the first filler component in the primary denitrification reactor 2 can not only provide a better anaerobic environment for the anaerobic ammonia-oxidizing bacteria, but also facilitate the uniform distribution of sludge in the tank body 21, thereby reducing the operating pressure on the embedded sedimentation tank.

[0068] Among them, the first filler component can use a hydrophilic filler such as a filling sponge filler, which is conducive to the attachment and growth of anaerobic ammonia oxidizing bacteria, prevents the loss of bacteria in the initial startup, is conducive to the proliferation of anaerobic ammonia oxidizing bacteria, forms a biofilm, and provides micro-aerobic and anaerobic conditions.

[0069] Specifically, the reaction formula of short-range nitrification is:

[0070] NH + 4+1.5O2→NO - 2+2H + +H2O;

[0071] The reaction equation for anaerobic ammonium oxidation is:

[0072] NH + 4+1.32NO - 2+0.066HCO - 3+0.12H + →1.0N2↑+0.26NO - 3+0.066C

[0073] H2O 0.5 N 0.15 +2.03H2O.

[0074] The above two reactions occur in the primary denitrification reactor 2. Both types of bacteria are autotrophic bacteria with long doubling times, especially the doubling time of anaerobic ammonia oxidizing bacteria, which is as long as 11 days. From the above reactions, it can be seen that aeration is required in the short-term nitrification stage, and the acid produced by the reaction requires alkalinity to neutralize. Anaerobic ammonia oxidizing bacteria are anaerobic bacteria and require an anaerobic environment to function. The reactor has a high requirement for dissolved oxygen. Therefore, pH and DO (Dissolved Oxygen) parameters need to be controlled in the reactor. The anaerobic environment of anaerobic ammonia oxidizing bacteria is created by biofilm and particles. At the same time, based on the analysis of the influent water quality, the nutrients necessary for the growth of anaerobic ammonia oxidizing bacteria are supplemented, such as Fe (Ⅱ), Ni (Ⅱ), Zn (Ⅱ), Cu (Ⅱ), Mn (Ⅱ) and Co (Ⅱ), which are indispensable trace elements in the growth and metabolism of anaerobic ammonia oxidizing microorganisms, as well as the supplementation of compounds containing P, K, Na, Mg, etc. required for the growth of microorganisms.

[0075] Therefore, in an optional embodiment, the primary denitrification reactor 2 also has a nutrient element introduction port.

[0076] It can be seen from the above reaction formula that when the reaction is removing ammonia nitrogen, a small amount of nitrate nitrogen will be produced, accounting for about 11% of the removed ammonia nitrogen concentration. At the same time, in order to ensure that nitrification stays in the short nitrification stage and prevent the proliferation of second-step nitrifying bacteria, ammonia nitrogen is converted into nitrate nitrogen, which cannot provide nitrite nitrogen substrate for anaerobic ammonia oxidizing bacteria. The ammonia nitrogen in the reactor maintains a certain concentration, usually not less than 50 mg / L. Therefore, after the high ammonia nitrogen wastewater passes through the primary denitrification reactor, the ammonia nitrogen concentration in the effluent is 50-150 mg / L, and it also contains nitrate nitrogen. The secondary denitrification reactor 4 can remove the nitrate nitrogen produced by the primary denitrification reactor 2, a small amount of ammonia nitrogen and nitrate nitrogen brought by nitrification reflux. The nitrification tank 5 can remove ammonia nitrogen, so that the ammonia nitrogen concentration is less than 25 mg / L and the total nitrogen is less than 70 mg / L, which meets the pipe standard.

[0077] Specifically, based on the need to supplement the nutrient solution required by anaerobic ammonia-oxidizing bacteria in the pool body 21, the reactor needs to control DO at 0-0.5 mg / L. The primary denitrification reactor 2 also has an acid / alkali solution injection port to control the pH between 7.2 and 8.3. At the same time, the ammonia nitrogen concentration is controlled at 50-150 mg / L, the nitrite nitrogen concentration is controlled below 10 mg / L, and the ratio of nitrate nitrogen generation to ammonia nitrogen degradation is detected to be below 0.15.

[0078] In an optional embodiment, if Figure 2 As shown, the first filler assembly includes a filler frame 27 and a plurality of filler units 24 placed in the filler frame 27. The filler frame 27 is supported at the bottom of the cell body 21 by a bracket 26. During processing, each filler unit 24 can be processed separately, which facilitates the preparation of the first filler assembly.

[0079] The above-mentioned filling frame 27 can be provided as one or more, and the number can be selected according to the height size of the cell body 21. When the filling frame 27 is provided as a plurality, the plurality of filling frames 27 are stacked in sequence from bottom to top.

[0080] The arrangement of the plurality of packing units 24 may be various. In an optional embodiment, in order to facilitate the more stable placement of each packing unit 24 in the packing frame 27, as shown in FIG. Figures 2 to 4 As shown, multiple packing units 24 are stacked layer by layer in a direction from the bottom to the top of the pool body 21; in two adjacent layers of packing units 24, the bottom of the upper packing unit 24 is snapped onto the top of the lower packing unit 24; each layer of packing units 24 includes multiple rows and columns of packing units 24, and adjacent packing units 24 are arranged closely together.

[0081] In the above embodiment, the bottom of the upper packing unit 24 is clamped to the top of the lower packing unit 24, and the lower packing unit 24 can limit the upper packing unit 24, and there is no need to set additional connecting parts such as cable ties to fix the upper and lower adjacent packing units 24, which facilitates the assembly of the packing units 24. In addition, since the adjacent packing units 24 in each layer of packing units 24 are closely arranged and play an auxiliary support role to each other, the adjacent packing units 24 can also be connected by cable ties, so that multiple packing units 24 form a whole and are stably placed in the pool body 21.

[0082] Based on the above embodiments, optionally, Figure 5 As shown, the packing unit 24 includes an outer frame 241, a packing body 242 and a plurality of retaining frames 243, wherein:

[0083] The top of the outer frame 241 is provided with an annular edge 2411, and the annular edge 2411 is provided with a limiting cavity. During assembly, the bottom of the outer frame 241 in the upper filling unit 24 can be inserted into the limiting cavity to limit the horizontal position of the upper filling unit 24;

[0084] Multiple retaining frames 243 are installed in parallel and at intervals in the outer frame 241, and divide the space in the outer frame 241 into multiple horizontally distributed water passage chambers 244 and multiple accommodating chambers 245. Each accommodating chamber 245 is provided with a filler body 242, which can be tied to the outer frame 241.

[0085] In the above embodiment, the accommodating cavity 245 can limit the position of the filler body 242. The purpose of setting the water passage cavity 244 is that if the filler body 242 is densely packed, and since the second aeration device 23 is arranged below the first filler assembly, the water passage cavity 244 can form a water passage gap between the filler body 242, thereby increasing the contact area between the filler body 242 and the sewage.

[0086] Specifically, Figure 4 As shown, the water passage chambers 244 and the accommodating chambers 245 can be distributed alternately, that is, a water passage chamber 244 is sandwiched between two accommodating chambers 245, so that both sides of the filler body 242 in the accommodating chamber 245 can fully contact with the sewage, avoiding concentrated accumulation of seasonings and improving the utilization rate of the filler.

[0087] In addition, the two adjacent filler bodies 242 of two horizontally adjacent filler units 24 are also separated by the water passage cavity 244 , so that a gap for water passage is formed between the two horizontally adjacent filler units 24 .

[0088] In an optional embodiment, the outer frame 241 includes an outer frame body 2412 and a support frame 2413 connected to the outer frame body 2412, the support frame 2413 is arranged horizontally, the top end of the support frame 243 is connected to the outer frame body 2412, the bottom end of the support frame 243 is connected to the support frame 2413, and a water flow cavity 244 is also formed between the bottom of the support frame 2413 and the outer frame body 2412, so that there is a water flow gap between two adjacent filler units 24, thereby increasing the contact area between the filler body 242 and the sewage.

[0089] In an optional embodiment, an adjustment component is connected between each retaining frame 243 and the outer frame 241 , and the adjustment component is used to adjust the distance between adjacent retaining frames 243 to adjust the width of the accommodating cavity 245 to accommodate filler bodies 242 of different sizes.

[0090] Specifically, the adjustment component may include a sleeve 246 arranged at the upper and lower ends of the retaining frame 243; the sleeve 246 at the lower end is sleeved on the outside of the beam of the support frame 2413 and can slide relative to the above-mentioned beam; the sleeve 246 at the upper end is sleeved on the outside of the beam of the outer frame 2412 and can slide relative to the above-mentioned beam; a fastener 247 is provided between each sleeve 246 and the beam, and the fastener 247 is threadedly matched with the sleeve 246. When the fastener 247 is loosened, the sleeve 246 can slide relative to the beam. When the fastener 247 is tightened, the fastener 247 can lock the position of the sleeve 246 relative to the beam. The fastener 247 can be a screw.

[0091] In addition, the agitator 22 may include a motor, a rotating shaft and blades 221. The motor is fixedly assembled on the top of the pool body 21. One end of the rotating shaft is connected to the power output shaft of the motor, and the other end extends into the pool body 21 and is connected to the blades 221. The rotating shaft can drive the blades 221 to rotate under the drive of the motor.

[0092] It should be noted that in order to avoid a large shear force on the sewage during the rotation of the agitator 22, the rotation speed of the agitator 22 needs to be set relatively low.

[0093] Preferably, the stirrer 22 is a hyperbolic stirrer.

[0094] The structure of the water tank 3 is described in detail below:

[0095] In an optional embodiment, if Figure 1 As shown, the bottom of the water tank 3 is conical.

[0096] The conical bottom of the box can collect the anaerobic ammonia-oxidizing bacteria carried out with the effluent of the primary denitrification reactor 2 and enter the secondary denitrification reactor 4 with the influent, thereby fully utilizing the anaerobic ammonia-oxidizing bacteria resources.

[0097] The structure of the nitrification tank 5 is specifically described below:

[0098] In an optional embodiment, a second filler assembly, a third aeration device and a second precipitator are provided in the nitrification tank 5, the third aeration device is installed at the bottom of the tank, the second filler assembly is installed in the tank and located above the third aeration device, and the second precipitator is installed at the outlet of the tank.

[0099] The above-mentioned nitrification tank 5 is similar to the primary denitrification reactor 2, and a precipitator is provided in the tank, which can save sludge return and reduce the energy consumption of the sludge return pump. At the same time, the particle shape in the sludge is protected from being destroyed by the return pump, so that the sludge has good sedimentation properties.

[0100] The structure of the second packing component may be similar to that of the first packing component, and will not be described in detail here to save space.

[0101] In an optional embodiment, the treatment system also includes a water outlet pool 7 connected to the water outlet of the nitrification pool 5, the water outlet pool 7 has a third water outlet and a fourth water outlet, the third water outlet is used to connect to the pipe network, and the fourth water outlet is connected to the top of the water tank 3.

[0102] When the total nitrogen in the effluent from the effluent pool 7 is higher than the pipe standard, the effluent can be returned to the water tank 3 through the fourth outlet, mixed with the effluent from the primary denitrification reactor 2 and enter the secondary denitrification reactor 4 for nitrate nitrogen removal to ensure that the total nitrogen in the effluent meets the discharge standard.

[0103] The embodiment of the second aspect of the present invention is to provide a method for treating high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater. The method for treating high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided by the embodiment of the second aspect of the present invention adopts the above-mentioned high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater treatment system, including:

[0104] The wastewater is discharged into the aeration sedimentation tank group 1, and the organic matter in the wastewater is removed through the aeration sedimentation tank group 1 and the pH value of the wastewater is adjusted;

[0105] The wastewater discharged from the aeration sedimentation tank group 1 is discharged into the primary denitrification reactor 2, and the wastewater undergoes a short-cut nitrification reaction and an anaerobic ammonium oxidation reaction in the primary denitrification reactor 2;

[0106] The wastewater discharged from the primary denitrification reactor 2 is discharged into the top of the water tank 3 and discharged from the bottom of the water tank 3 into the secondary denitrification reactor 4 for denitrification reaction coupled with short-range denitrification reaction and anaerobic ammonium oxidation reaction;

[0107] The wastewater discharged from the secondary denitrification reactor 4 is discharged into the nitrification tank 5, and the ammonia nitrogen in the wastewater is oxidized into nitrate nitrogen in the nitrification tank 5.

[0108] The method for treating high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided in the embodiment of the second aspect of the present invention adopts the system for treating high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided in the embodiment of the first aspect of the present invention, thereby having all the beneficial effects of the system for treating high-ammonia-nitrogen and low-carbon-nitrogen ratio wastewater provided in the embodiment of the first aspect of the present invention.

[0109] The following is a specific example of a method for treating the above-mentioned high ammonia nitrogen and low carbon nitrogen ratio wastewater:

[0110] The water used in the pilot test was taken from the dewatered filtrate after anaerobic digestion of sludge from a sludge plant. The sludge was not pretreated before anaerobic digestion. The water quality of the dewatered filtrate (biogas slurry) was as follows:

[0111] CODcr: 300-700 mg·L －1 , NH + 4-N is 500-1000 mg·L －1 , total nitrogen content is 500-1000 mg·L －1 , the total phosphorus content is less than 1 mg·L －1 , suspended matter content is 300-800mg·L －1 , pH6-7.

[0112] The pilot test device is designed to have a water inlet of 1-2m 3 / day, the processing capacity is 1kgN / d. The process flow refers to the above embodiment. The biogas slurry is first lifted by a pump and enters the pre-aeration tank 11. The aeration time is about 2h. During this period, NaOH is added to adjust the pH to about 8. After the aeration is completed, it enters the coagulation sedimentation tank and polyaluminium chloride solution is added. The content of polyaluminium chloride is about 10%, and the dosage per ton of water is 200-500ml. The suspended solids content of the effluent after precipitation is 30-100mg·L －1 , COD from 500mg·L －1 Reduced to 400 mg·L －1 About, and then enters the primary denitrification reactor 2.

[0113] The primary denitrification reactor 2 is directly inoculated with AOB bacteria and Anammox granular bacteria. The filler is a hydrophilic sponge filler. The startup is completed by controlling DO, pH and nitrite nitrogen concentration. Anammox bacteria attach and grow on the filler. The outside of the biofilm is AOB bacteria, which improves the anaerobic environment for the Anammox bacteria in the biofilm. In addition, there are suspended sludge and granular sludge in the reactor. The three coexist in the primary denitrification reactor 2, so that AOB bacteria and Anammox bacteria can play various roles in the aerated environment to complete the removal of ammonia nitrogen. At the beginning of the startup, the reactor was inoculated with flocculent sludge containing anaerobic ammonia-oxidizing bacteria, but NOB bacteria proliferated during operation, which was difficult to recover and had to be restarted. Through a small-scale experiment on the short-range nitrification-anaerobic ammonia oxidation process, a system in which biofilm, granular sludge and suspended sludge coexisted was finally selected. The process has been running for 2 years and no NOB proliferation has occurred. The DO in the reactor is maintained at 0-0.5 mg·L by adjusting the aeration volume －1 The pH in the reactor was controlled at about 7.5-8 by adding sodium carbonate solution, the water temperature was controlled at 25℃-35℃, and the nitrite nitrogen concentration was maintained at 10mg·L －1 Below, the effluent ammonia nitrogen is controlled at 50-150 mg·L －1 , nitrate nitrogen concentration is 40-80 mg·L －1 , COD200-300mg·L －1 In addition, since a large amount of iron salts are added to the sludge during the plate and frame dehydration process after anaerobic digestion, the phosphorus content in the wastewater is reduced. At this stage, potassium dihydrogen phosphate solution needs to be added to supplement the phosphorus required for microbial growth, and the phosphorus concentration in the primary denitrification reactor is controlled at 2-5 mg·L －1 The reactor is provided with an embedded sedimentation tank, and the effluent enters the water tank 3.

[0114] The water tank 3 is set as a vertical flow sedimentation tank structure. The suspended matter in the effluent of the primary denitrification reactor 2 will continue to be further separated in the water tank 3. The suspended matter contains some anaerobic ammonium oxidizing bacteria. At the beginning of the process startup, the precipitated sludge will return to the primary denitrification reactor 2. When the startup is completed, the sludge enters the secondary denitrification reactor 4 with the wastewater. At the beginning of the experiment, the reactor was inoculated with anaerobic ammonium oxidizing granular sludge, and the carbon source was selected as sodium acetate to directly start the short-cut denitrification anaerobic ammonium oxidation process. The effluent was added with carbon source at a C / N ratio of about 2, which can achieve the removal of ammonia nitrogen and nitrate nitrogen. The total nitrogen in the effluent was below 70 mg / L. However, after changing to a composite carbon source, the contribution rate of the short-cut denitrification-anaerobic ammonium oxidation denitrification reaction in the total nitrogen removal gradually decreased. Therefore, the secondary denitrification inoculation was changed to laboratory-cultured denitrification granular sludge, and the startup was completed directly. Moreover, the addition of composite carbon source at a C / N ratio of 3-3.5 can remove most of the nitrate nitrogen in the influent. The nitrate nitrogen in the effluent is about 10 mg / L, and the ammonia nitrogen in the effluent is also lower than that in the primary denitrification reactor, accounting for about 10%-20%, indicating that a short-range denitrification-anaerobic ammonia oxidation reaction also occurred. Therefore, considering the economy and operation stability, the secondary denitrification reactor 4 selects a denitrification process based on denitrification, supplemented by a short-range denitrification-anaerobic ammonia oxidation reaction, which is also a secondary utilization of the anaerobic ammonia oxidizing bacteria in the effluent of the primary denitrification reactor 2. The secondary denitrification reactor 4 uses the UASB (Up-flow Anaerobic Sludge Bed / Blanket) structure, which has a good interception effect on the denitrification granular sludge, and the volumetric load is more than 5 times that of the traditional AO process. The ammonia nitrogen in the effluent of the secondary reactor is 30-50 mg·L －1 , nitrate nitrogen is 0-15 mg·L －1 , nitrite nitrogen at 0-5mg / L, COD at 300mg·L －1 The effluent enters the nitrification tank 5.

[0115] The nitrification tank 5 is mainly used to oxidize the ammonia nitrogen in the effluent of the secondary denitrification reactor 4 into nitrate nitrogen. The main bacteria that undergo this reaction are AOB and NOB, which are autotrophic bacteria with a long doubling time. Since the denitrification sludge of the secondary denitrification reactor 4 is retained in the secondary denitrification reactor 4 through the three-phase separator, the sludge discharge of the nitrification tank 5 is reduced and the sludge age is long, so that the number of nitrifying bacteria in the sludge is much higher than that of nitrifying bacteria in the traditional AO system, the sludge load is high, the tank capacity is small, and the floor space is small. Based on the ammonia nitrogen concentration of the effluent of the primary denitrification reactor 2 of the denitrification system, the proportion of the effluent of the nitrification tank returned to the intermediate water tank is adjusted to ensure that the ammonia nitrogen in the effluent of the nitrification tank is controlled at 15 mg·L －1 Below, total nitrogen concentration is 60mg·L －1 Below, COD at 500mg·L －1 the following.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio, characterized in that: It comprises an aeration sedimentation tank group (1), a primary denitrification reactor (2), a water tank (3), a secondary denitrification reactor (4) and a nitrification tank (5) which are sequentially arranged along the wastewater treatment direction; The aeration sedimentation tank group (1) is used to remove organic matter and suspended solids in sewage, reduce the concentration of metal ions, and adjust the pH value of sewage; The primary denitrification reactor (2) is connected to the aeration sedimentation tank group (1), and the primary denitrification reactor (2) is used to perform a short-cut nitrification reaction and an anaerobic ammonium oxidation reaction; The top of the water tank (3) is connected to the primary denitrification reactor (2), and the bottom of the water tank (3) is connected to the secondary denitrification reactor (4) via a first pipeline (6), and the first pipeline (6) is also used to communicate with a carbon source; The secondary denitrification reactor (4) is used to carry out a denitrification reaction coupled with a short-range denitrification reaction and an anaerobic ammonium oxidation reaction. The secondary denitrification reactor (4) has a first water outlet connected to the first pipeline (6) and a second water outlet connected to the nitrification tank (5). The nitrification tank (5) is used to oxidize ammonia nitrogen in the wastewater into nitrate nitrogen.

2. The system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio according to claim 1, characterized in that: The aeration sedimentation tank group (1) comprises a pre-aeration tank (11) and a sedimentation tank (12); The pre-aeration tank (11) has an acid / alkali solution introduction port, and a first aeration device (111) is provided at the bottom of the pre-aeration tank (11); The sedimentation tank (12) has a coagulant introduction port and / or a flocculant introduction port.

3. The system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio according to claim 1, characterized in that: The primary denitrification reactor (2) comprises a tank body (21), an agitator (22), a second aeration device (23), a first filler assembly and a first precipitator (25), wherein the second aeration device (23) is installed at the bottom of the tank body (21), the first filler assembly is installed in the tank body (21) and is located above the second aeration device (23), the agitator (22) extends into the tank body (21), and the first precipitator (25) is installed at the outlet of the tank body (21).

4. The system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio according to claim 3, characterized in that: The first filler assembly comprises a filler frame (27) and a plurality of filler units (24) placed in the filler frame (27); the filler frame (27) is supported at the bottom of the cell body (21) by a bracket (26); and the plurality of filler units (24) are stacked and arranged layer by layer in the filler frame in a direction from the bottom of the cell body (21) to the top; In two adjacent layers of the packing units (24), the bottom of the packing unit (24) in the upper layer is clamped to the top of the packing unit (24) in the lower layer; Each layer of the packing units (24) comprises a plurality of rows and columns of the packing units (24), and adjacent packing units (24) are arranged in close proximity.

5. The system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio according to claim 4, characterized in that: The packing unit (24) comprises an outer frame (241), a packing body (242) and a plurality of retaining frames (243); A limiting cavity is provided around the top of the outer frame (241), and the limiting cavity is used for the bottom of the outer frame (241) in the upper filling unit (24) to extend into; The plurality of retaining frames (243) are installed in parallel and at intervals in the outer frame (241), and divide the space in the outer frame (241) into a plurality of horizontally distributed water passage chambers (244) and a plurality of accommodating chambers (245), and each accommodating chamber (245) is provided with the filler body (242).

6. The system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio according to claim 5, characterized in that: An adjustment component is connected between each of the blocking frames (243) and the outer frame (241), and the adjustment component is used to adjust the distance between adjacent blocking frames (243).

7. The system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio according to claim 1, characterized in that: The primary denitrification reactor (2) further comprises an acid / alkali solution introduction port and / or a nutrient element introduction port.

8. The system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio according to any one of claims 1 to 7, characterized in that: The bottom of the water tank (3) is conical.

9. The system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio according to any one of claims 1 to 7, characterized in that: The treatment system further comprises a water outlet pool (7) connected to the water outlet of the nitrification pool (5), wherein the water outlet pool (7) has a third water outlet and a fourth water outlet, wherein the third water outlet is used to be connected to a pipe network, and the fourth water outlet is connected to the top of the water tank (3).

10. A method for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio using the system for treating wastewater with high ammonia nitrogen and low carbon nitrogen ratio as claimed in any one of claims 1 to 9, characterized in that: include: Discharging the wastewater into the aeration sedimentation tank group (1), removing organic matter and suspended solids in the wastewater, reducing the concentration of metal ions, and adjusting the pH value of the wastewater through the aeration sedimentation tank group (1); The wastewater discharged from the aeration sedimentation tank group (1) is discharged into the primary denitrification reactor (2), and the wastewater undergoes a short-cut nitrification reaction and an anaerobic ammonium oxidation reaction in the primary denitrification reactor (2); The wastewater discharged from the primary denitrification reactor (2) is discharged into the top of the water tank (3) and then discharged from the bottom of the water tank (3) into the secondary denitrification reactor (4) to perform a denitrification reaction coupled with a short-range denitrification reaction and an anaerobic ammonium oxidation reaction; The wastewater discharged from the secondary denitrification reactor (4) is discharged into the nitrification tank (5) for nitrification reaction, and the ammonia nitrogen in the wastewater is oxidized into nitrate nitrogen in the nitrification tank (5).

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